Docs: Add links, fix grammar, formatting, wording (#22381)

* Docs: Add links, fix grammar, formatting, wording

- Add links to theme files and technology references
- Adjust formatting to be consistent, e.g., syntax highlighting, section spacing
- Fix misc grammar, punctuation
- Fix SASS -> Sass

Co-Authored-By: Arve Knudsen <arve.knudsen@gmail.com>
Co-Authored-By: Diana Payton <52059945+oddlittlebird@users.noreply.github.com>

contribute/style-guides/themes.md

@@ -2,11 +2,22 @@
 
 ## Overview
 
-**Themes are implemented in Typescript.** That's because our goal is to share variables between Grafana Typescript code and SASS files. Theme definitions are located in `packages/grafana-ui/src/themes/[default|dark|light].ts` files. `default.ts` file holds common variables like typography and spacing definitions, while `[light|dark].ts` primarily specify colors used in themes.
+**Themes are implemented in Typescript.** That's because our goal is to share variables between Grafana TypeScript and [Sass](https://sass-lang.com/) code. Theme definitions are located in the following files:
+
+- [packages/grafana-ui/src/themes/dark.ts](../../packages/grafana-ui/src/themes/dark.ts)
+- [packages/grafana-ui/src/themes/default.ts](../../packages/grafana-ui/src/themes/default.ts)
+- [packages/grafana-ui/src/themes/light.ts](../../packages/grafana-ui/src/themes/light.ts)
+
+The `default.ts` file holds common variables like typography and spacing definitions, while `[light|dark].ts` primarily specify colors used in themes.
 
 ## Usage
+
+This section provides usage guidelines.
+
 ### Using themes in React components
 
+Here's how to use Grafana themes in React components.
+
 #### Using `ThemeContext` directly
 
 ```tsx
@@ -26,12 +37,11 @@ const Foo: React.FunctionComponent<FooProps> = () => {
 
   // Your component has access to the theme variables now
 }
-
 ```
 
 #### Using `withTheme` higher-order component (HOC)
 
-With this method your component will be automatically wrapped in `ThemeContext.Consumer` and provided with current theme via `theme` prop. Component used with `withTheme` must implement `Themeable` interface.
+With this method your component will be automatically wrapped in `ThemeContext.Consumer` and provided with current theme via `theme` prop. Components used with `withTheme` must implement the `Themeable` interface.
 
 ```ts
 import  { ThemeContext, Themeable } from '@grafana/ui';
@@ -43,7 +53,7 @@ const Foo: React.FunctionComponent<FooProps> = () => ...
 export default withTheme(Foo);
 ```
 
-### Test components that use ThemeContext
+### Test components that use `ThemeContext`
 
 When implementing snapshot tests for components that use the `withTheme` HOC, the snapshot will contain the entire theme object. Any change to the theme renders the snapshot outdated.
 
@@ -73,9 +83,11 @@ describe('MyComponent', () => {
 });
 ```
 
-### Using themes in Storybook
+### Using themes in [Storybook](https://storybook.js.org/)
 
-All stories are wrapped with `ThemeContext.Provider` using global decorator. To render `Themeable` component that's not wrapped by `withTheme` HOC you either create a new component in your story:
+All stories are wrapped with `ThemeContext.Provider` using a global decorator. To render a `Themeable` component that isn't wrapped by a `withTheme` HOC, either create a new component in your story, or use the `renderComponentWithTheme` helper.
+
+#### Create a new component:
 
 ```tsx
 // Foo.story.tsx
@@ -86,7 +98,7 @@ FooStories.add('Story' () => {
 });
 ```
 
-or use `renderComponentWithTheme` helper:
+#### Use `renderComponentWithTheme` helper:
 
 ```tsx
 // Bar.story.tsx
@@ -98,29 +110,42 @@ BarStories.add('Story' () => {
 
 ### Using themes in Angular code
 
-There should be very few cases where theme would be used in Angular context. For this purpose there is a function available that retrieves current theme: `import { getCurrentTheme } from app/core/utils/ConfigProvider`. Angular components should be migrated to React, or if that's not possible at the moment, styled using SASS.
+There should be very few cases where a theme would be used in an Angular context. For this purpose, there is a function available that retrieves the current theme:
+
+```ts
+import { getCurrentTheme } from app/core/utils/ConfigProvider
+```
 
+Angular components should be migrated to React, or if that's not possible at the moment, styled using Sass.
 
 ## FAQ
-### How can I modify SASS variable files?
+
+This section provides insight into frequently-asked questions.
+
+### How can I modify Sass variable files?
+
 > For the following to apply you need to run `yarn dev` task.
 
-`[_variables|_variables.dark|_variables.light].generated.scss` files are the ones that are referenced in the main SASS files for SASS variables to be available. **These files are automatically generated and should never be modified by hand!**.
+`[_variables|_variables.dark|_variables.light].generated.scss` files are the ones that are referenced in the main Sass files for Sass variables to be available. **These files are automatically generated and should never be modified by hand!**
 
-#### If you need to modify *SASS variable value* you need to modify corresponding Typescript file that is a source of the variables:
+#### If you need to modify a *Sass variable value* you need to modify the corresponding Typescript file that is the source of the variables:
 - `_variables.generated.scss` - modify `grafana-ui/src/themes/default.ts`
 - `_variables.light.generated.scss` - modify `grafana-ui/src/themes/light.ts`
 - `_variables.dark.generated.scss` - modify `grafana-ui/src/themes/dark.ts`
 
-#### If you need to *add new variable* to SASS variables you need to modify corresponding template file:
+#### If you need to *add new variable* to Sass variables you need to modify corresponding template file:
 - `_variables.generated.scss` - modify `grafana-ui/src/themes/_variables.scss.tmpl.ts`
 - `_variables.light.generated.scss` - modify `grafana-ui/src/themes/_variables.light.scss.tmpl.ts`
 - `_variables.dark.generated.scss` - modify `grafana-ui/src/themes/_variables.dark.scss.tmpl.ts`
 
 
 ## Limitations
-### You must ensure ThemeContext provider is available in a React tree
-  By default all react2angular directives have `ThemeContext.Provider` ensured. But, there are cases where we create another React tree via `ReactDOM.render`. This happens in case of graph legend rendering and `ReactContainer` directive. In such cases theme consumption will fail. To make sure theme context is available in such cases, you need to wrap your rendered component with ThemeContext.Provider using `provideTheme` function:
+
+This section describes limitations with Grafana's theming system.
+
+### You must ensure `ThemeContext` provider is available in a React tree
+
+By default all react2angular directives have `ThemeContext.Provider` ensured. But, there are cases where we create another React tree via `ReactDOM.render`. This happens in the case of graph legend rendering and the `ReactContainer` directive. In such cases theme consumption will fail. To make sure theme context is available in such cases, you need to wrap your rendered component with ThemeContext.Provider using the `provideTheme` function:
 
 ```ts
 // graph.ts