[v10.0.x] [feat] docs; update admonition syntax (#68857)

[feat] docs; update admonition syntax (#68842)

* [feat] docs; update admonition syntax

- Standardizes according to style conventions: https://grafana.com/docs/writers-toolkit/style-guide/style-conventions/#admonitions
- Prepares docs for better, uniform admonition style.

* Remove false positives and irregularities

* false positive removal

* Update docs/sources/datasources/mysql/_index.md

* Update docs/sources/developers/angular_deprecation/angular-plugins.md

* fix link errors

* Prettify some nested blockquotes

* remoe unnecessary admonition

(cherry picked from commit 1c4bb9ca00)

Co-authored-by: Matt Dodson <47385188+MattDodsonEnglish@users.noreply.github.com>

docs/sources/datasources/graphite/template-variables/index.md

@@ -104,7 +104,9 @@ For example, `apps.$app.servers.*` uses the variable `$app` in its query definit
 
 ### Use `__searchFilter` to filter query variable results
 
-> **Note:** Available in Grafana v6.5 and higher.
+{{% admonition type="note" %}}
+Available in Grafana v6.5 and higher.
+{{% /admonition %}}
 
 You can use `__searchFilter` in the query field to filter the query result based on what the user types in the dropdown select box.
 The default value for `__searchFilter` is `*` if you've not entered anything, and `` when used as part of a regular expression.