Docs: fix image, add nginx code type (#23387)

docs/sources/_index.md

@@ -8,7 +8,8 @@ aliases = ["/docs/grafana/v1.1", "/docs/grafana/latest/guides/reference/admin",
 
 # Grafana documentation
 
-<h2>Installing Grafana</h2>
+## Installing Grafana
+
 <div class="nav-cards">
     <a href="{{< relref "installation/debian.md" >}}" class="nav-cards__item nav-cards__item--install">
         <div class="nav-cards__icon fa fa-linux">
@@ -26,7 +27,7 @@ aliases = ["/docs/grafana/v1.1", "/docs/grafana/latest/guides/reference/admin",
         <h5>Install on Windows</h5>
     </a>
     <a href="{{< relref "installation/docker.md" >}}" class="nav-cards__item nav-cards__item--install">
-        <img src="/img/docs/logos/icon_docker.png">
+        <img src="/static/img/logos/logo-docker.svg">
         <h5>Run Docker image</h5>
     </a>
     <a href="https://grafana.com/cloud/grafana" class="nav-cards__item nav-cards__item--install">
@@ -41,7 +42,7 @@ aliases = ["/docs/grafana/v1.1", "/docs/grafana/latest/guides/reference/admin",
     </a>
 </div>
 
-<h2>Guides</h2>
+## Guides
 
 <div class="nav-cards">
     <a href="{{< relref "guides/what-is-grafana.md" >}}" class="nav-cards__item nav-cards__item--guide">
@@ -71,7 +72,8 @@ aliases = ["/docs/grafana/v1.1", "/docs/grafana/latest/guides/reference/admin",
 
 </div>
 
-<h2>Data source guides</h2>
+## Data source guides
+
 <div class="nav-cards">
     <a href="{{< relref "features/datasources/graphite.md" >}}" class="nav-cards__item nav-cards__item--ds">
       <img src="/img/docs/logos/icon_graphite.svg" >

docs/sources/installation/behind_proxy.md

@@ -38,7 +38,7 @@ domain = foo.bar
 Nginx is a high performance load balancer, web server and reverse proxy: https://www.nginx.com/
 
 #### Nginx configuration with HTTP and Reverse Proxy enabled
-```bash
+```nginx
 server {
   listen 80;
   root /usr/share/nginx/html;
@@ -62,7 +62,7 @@ root_url = https://foo.bar
 
 Instead of http://foo.bar:3000/?orgId=1, this configuration will redirect all HTTP requests to HTTPS and re-write the URL so that port 3000 isn't visible and will result in https://foo.bar/?orgId=1
 
-```bash
+```nginx
 server {
   listen 80;
   server_name foo.bar;
@@ -98,7 +98,7 @@ root_url = %(protocol)s://%(domain)s/grafana/
 ```
 
 #### Nginx configuration with sub path
-```bash
+```nginx
 server {
   listen 80;
   root /usr/share/nginx/www;