Update mysql.md with correct anchor link to "how services are linked"
What does this MR do?
Fixes the broken anchor url to the "how services are linked" section.
- Apply the correct labels and milestone
- Crosslink the document from the higher-level index
- Crosslink the document from other subject-related docs
Feature moving tiers? Make sure the change is also reflected in
- Correctly apply the product badges and tiers
Port the MR to EE (or backport from CE): always recommended, required when the
- Your team's review (required)
- PM's review (recommended, but not a blocker)
- Technical writer's review (required)
- Merge the EE-MR first, CE-MR afterwards