[extension-docs] Fix broken link

[mikesg1t]

trafficstars

Fixes issue #2434

Changes proposed in this pull request:

• add [docs-service-workers]: /docs/extensions/mv3/service_workers/ as a footer link.

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[chrome-devrel-review-bot]

Hello! This is an automated review by our custom reviewbot. It updates automatically when code or GitHub comments in this pull request are created or updated.

Requested changes

If there are any common problems with the content files you created or modified, they will be listed here.

site/en/docs/webstore/troubleshooting/index.md

• Please change your usage of the following words:
  • Do not use master. Affected lines: 1026, 1027, 1208

[sofiayem]

mikesg1t Thank you for your contribution! Please accept the Google CLA.