[7.9] [DOCS] Fix hard-coded accessibility link (#209611) (#209641)

# Backport

This will backport the following commits from `7.15` to `7.9`:
- [[DOCS] Fix hard-coded accessibility link
(#209611)](#209611)

<!--- Backport version: 9.6.4 -->

### Questions ?
Please refer to the [Backport tool
documentation](https://github.com/sorenlouv/backport)

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Author: lcawl

docs/developer/best-practices/index.asciidoc

@@ -20,7 +20,7 @@ Are you planning with scalability in mind?
 
 Did you know {kib} makes a public statement about our commitment to
 creating an accessible product for people with disabilities?
-https://www.elastic.co/guide/en/kibana/master/accessibility.html[We do]!
+<<accessibility,We do>>!
 It’s very important all of our apps are accessible.
 
 * Learn how https://elastic.github.io/eui/#/guidelines/accessibility[EUI