Implement content linting rules on the Handbook

Problem to solve

The GitLab handbook is the canonical reference for how GitLab operates and should reflect the company's values and standards of quality. We have well-documented style guidelines for prose, but there is no way of enforcing or even alerting contributors of potential errors.

Proposal

Implement Vale or other prose linting library that checks against a list of rules and surfaces warnings or errors in the CI Pipeline for the GitLab handbook.

Details

This is being raised in part because of feedback from the GitLab Slack channel #replace-whitelist-blacklist.

We'll want to implement general rules based on our style guides, but we specifically want to call out the following rules:

• Fail pipeline for use of blacklist or whitelist and suggest Blocklist or Allowlist
• Flag gendered language and suggest more inclusive alternatives

References

• GitLab Handbook Style Guide
• General Writing Style Guidelines