Docs titles clipped on the left side - anchors not accessible

[abhishek2303]

Fixes the visibility of the anchor titles documentation UI which is currently clipped. This is done by assigning CSS overflow: visible property to the parent component - component-overview.

Fixes 20687

Before

After

The approach mentioned in 20687 suggests removing the margin of -30px from header-link. This would make the header text start after 30px with nothing in between. The approach in this PR is taken to overcome this visual oddity.

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[abhishek2303]

@googlebot I signed it!

[crisbeto]

LGTM. I also confirmed that this doesn't regress #856.