Docs: update content to work with website repo (#20693)

Updates the docs to work with the website repo - mainly 
relative link updates.
Adds a menu.yaml file to build the sidebar menu (no longer 
using front matter weight).

docs/sources/tutorials/_index.md

@@ -12,7 +12,7 @@ This section of the docs contains a series for tutorials and stack setup guides.
 
 ## Articles
 
-- [Running Grafana behind a reverse proxy]({{< relref "behind_proxy.md" >}})
+- [Running Grafana behind a reverse proxy]({{< relref "../installation/behind_proxy.md" >}})
 - [API Tutorial: How To Create API Tokens And Dashboards For A Specific Organization]({{< relref "api_org_token_howto.md" >}})
 - [How to Use IIS with URL Rewrite as a Reverse Proxy for Grafana on Windows]({{< relref "iis.md" >}})
 - [How to integrate Hubot with Grafana]({{< relref "hubot_howto.md" >}})