docs(providers): fix OAuth wording in self-hosted GitLab setup

[xgbtxy]

Issue for this PR

Closes #44308

Type of change

• Bug fix
• New feature
• Refactor / code improvement
• Documentation

What does this PR do?

Corrects the OAuth casing and grammar in the self-hosted GitLab setup instructions. The wording now matches the heading directly above it and the other OAuth references on the page.

How did you verify your code works?

• bun run --cwd packages/web build (Bun 1.3.14)
• git diff --check
• Verified the generated Providers page contains the corrected sentence

Screenshots / recordings

Not applicable — documentation-only change.

Checklist

• I have tested my changes locally
• I have not included unrelated changes in this PR

[Copilot]

Pull request overview

Updates the Providers documentation to correct OAuth casing and grammar in the self-hosted GitLab setup section, aligning the sentence with the “OAuth for Self-Hosted instances” heading and other occurrences in the page.

Changes:

• Fixes Oauth → OAuth casing in the self-hosted GitLab OAuth instructions.
• Improves grammar from “make OAuth working” → “make OAuth work”.

---

💡 Add a code-review agent skill or configure MCP servers for context-aware, tailored reviews. Learn more in the docs.

[github-actions]

Thanks for updating your PR! It now meets our contributing guidelines. 👍

[Enough1122]

AI code review — automated review for reference, author can ignore or act on any point.

Correct fix — Oauth working → OAuth work matches the casing of the heading directly above ("OAuth for Self-Hosted instances") and reads naturally.

One optional adjacent polish in the same sentence (packages/web/src/content/docs/providers.mdx, ~line 1012): "…callback URL http://127.0.0.1:8080/callback and following scopes:" would read slightly more smoothly as "…and the following scopes:". Entirely optional — good to merge as-is otherwise.