* moved some content into other topics

* Update variable-value-tags.md

* Update variable-selection-options.md

* Update add-query-variable.md

* Update templates-and-variables.md

* Create add-custom-variable.md

* Update menu.yaml

* Update templates-and-variables.md

* Update templates-and-variables.md

* editing content

* Create add-text-box-variable.md

* added links

* content updates

* update-content

* Update templates-and-variables.md

* Update menu.yaml

* Update add-constant-variable.md

* Update add-constant-variable.md

* Update docs/sources/variables/add-query-variable.md

Co-authored-by: Arve Knudsen <arve.knudsen@gmail.com>

* Update docs/sources/variables/variable-value-tags.md

Co-authored-by: Arve Knudsen <arve.knudsen@gmail.com>

* Update docs/sources/variables/variable-value-tags.md

Co-authored-by: Arve Knudsen <arve.knudsen@gmail.com>

* Update docs/sources/variables/variable-value-tags.md

Co-authored-by: Arve Knudsen <arve.knudsen@gmail.com>

Co-authored-by: Arve Knudsen <arve.knudsen@gmail.com>