Update links for "Embedding Grafana charts"

What does this Merge Request do?

The documentation was moved in gitlab!36615 (merged) so let's update the stale links.

Refs gitlab!37844 (comment 386237026)

Merge Request checklist

• [-] Tests added for new functionality. If not, please raise Issue to follow-up.
• [-] This change is backward compatible. If not, please include steps to communicate to our users.
• Documentation added/updated, if needed.
• [-] gdk doctor test added, if needed.