chore(compass-indexes): change docs link to nav to rolling index builds directly COMPASS-9276

[nbbeeken]

Description

Update URL for "learn more" on rolling index builds

Checklist

• [/] New tests and/or benchmarks are included
• Documentation is changed or added
• [/] If this change updates the UI, screenshots/videos are added and a design review is requested
• [/] I have signed the MongoDB Contributor License Agreement (https://www.mongodb.com/legal/contributor-agreement)

Motivation and Context

• Bugfix
• New feature
• Dependency update
• Misc

Open Questions

None

Dependents

None

Types of changes

• Backport Needed
• Patch (non-breaking change which fixes an issue)
• Minor (non-breaking change which adds functionality)
• Major (fix or feature that would cause existing functionality to change)