Doc: Adding information about datasource UID enforcement (#92659)

* Adding information about datasource UID enforcement

* Style and content fixes (#92667)

This fixes:
- datasource to data source as per our style guide
- some other minor typos
- style and content

* fixing prettier lint

---------

Co-authored-by: Irene Rodriguez <irene.rodriguez@grafana.com>

docs/sources/upgrade-guide/upgrade-v11.2/index.md

@@ -19,4 +19,51 @@ weight: 1000
 
 {{< docs/shared lookup="upgrade/upgrade-common-tasks.md" source="grafana" version="<GRAFANA_VERSION>" >}}
 
+## Ensure that your data source UIDs are following the correct standard
+
+We have had a standard ways to define UIDs for Grafana objects for years (at least [since Grafana 5](https://github.com/grafana/grafana/issues/7883)). While all of our internal code is complying to this format, we did not yet had strict enforcement of this format in REST APIs and provisioning paths that allow creation and update of data sources.
+
+In Grafana `11.1` we [introduced](https://github.com/grafana/grafana/pull/86598) a warning that is sent to Grafana server logs every time a data source instance is being created or updated using an invalid UID format.
+
+In Grafana `11.2` we [added](https://github.com/grafana/grafana/pull/89363/files) a new feature flag called `failWrongDSUID` that is turned off by default. When enabled, the REST APIs and provisioning will start rejecting and requests to create or update datasource instances that have a wrong UID.
+
+In Grafana `11.5`, we are going to turn feature flag `failWrongDSUID` on by default, but there will still be an option to turn it off.
+
+In Grafana `12`, this will be the default behavior and will not be configurable.
+
+### Correct UID format
+
+You can find the exact regex definition [here](https://github.com/grafana/grafana/blob/c92f5169d1c83508beb777f71a93336179fe426e/pkg/util/shortid_generator.go#L32-L45).
+
+A data source UID can only contain:
+
+- latin characters (`a-Z`)
+- numbers (`0-9`)
+- dash symbols (`-`)
+
+### How can I know if I am affected?
+
+- You can fetch all your data sources via `/api/datasources` API ([docs](https://grafana.com/docs/grafana/latest/developers/http_api/data_source/#get-all-data-sources)). Look into `uid` fields comparing it to the correct format. Below you'll find a script that could help, but please note it is missing authentication that you would [have to add yourself](https://grafana.com/docs/grafana/latest/developers/http_api/#authenticating-api-requests).
+
+```
+curl http://localhost:3000/api/datasources | jq '.[] | select((.uid | test("^[a-zA-Z0-9\\-_]+$") | not) or (.uid | length > 40)) | {id, uid, name, type}'
+```
+
+- Alternatively, you can check the server logs for the `Invalid datasource uid` ([reference](https://github.com/grafana/grafana/blob/68751ed3107c4d15d33f34b15183ee276611785c/pkg/services/datasources/service/store.go#L429))
+
+### What can I do if I am affected?
+
+You will need to create a new data source with the correct UID and update your dashboards and alert rules to use it.
+
+### How can I update my dashboards to use the new or updated data source?
+
+1. Go to the dashboard using this data source and update it by selecting the new or updated data source from the picker below your panel.
+2. Update the dashboard's JSON model directly via search and replace. Navigate to [dashboard json model](https://grafana.com/docs/grafana/latest/dashboards/build-dashboards/view-dashboard-json-model/) and carefully replace all the instances of old `uid` with the newly created `uid`.
+
+{{< figure src="/media/docs/grafana/screenshot-grafana-11-datasource-uid-enforcement.png" alt="Updating JSON Model of a Dashboard">}}
+
+### How can I update my alert rules to use the new or updated data source?
+
+Open the alert rule you want to adjust and search for the data source that is being used for the query/alert condition. From there, select the new data source from the dropdown menu and save the alert rule.
+
 ## Technical notes