[[ DO NOTY MERGE ]] Update ATT&CK coverage URL(s) in docs/ATT&CK-coverage.md

[github-actions[bot]]

Update ATT&CK coverage URL(s) in docs/ATT&CK-coverage.md

• Autogenerated from job attack-coverage-update: pr.

[shashank-elastic]

Tested Workflow PR as part of PR https://github.com/elastic/detection-rules/pull/4077

This is built out of private branch, so we can ignore the Merge.