Update anchors to resolve MD lint errors

What does this MR do?

With the latest markdown-link-check release, they added check for anchors. The MR resolves found issues with anchors in GET.

• When header has symbols like /, some symbols can be escaped with --
• When header has - in it, Markdown is not able to resolve it even with escaping => updated to use () instead of -

Related issues

Author's checklist

When ready for review, the Author applies the workflowready for review label and mention @gl-quality/get-maintainers:

• Merge request:
  • Corresponding Issue raised and reviewed by the GET maintainers team.
  • Merge Request Title and Description are up to date, accurate, and descriptive
  • MR targeting the appropriate branch
  • MR has a green pipeline
  • MR has no new security alerts in the widget from the Secret Detection and IaC Scan (SAST) jobs.
• Code:
  • Documentation created/updated in the same MR.