docs: escape braces to avoid Liquid tag handling

[cho-m]

Can see missing text at https://docs.brew.sh/Cask-Cookbook#file-preparation-steps

Content may use the , and tokens, which are expanded at install time; any other is left verbatim.

Also remove test error doc from old Linuxbrew. This information is better to find elsewhere and the Ubuntu wiki is being decommissioned

• https://discourse.ubuntu.com/t/a-new-ubuntu-wiki-part-1-announcement/72729

---

• Have you followed our Contributing guidelines?
• Have you checked for other open Pull Requests for the same change?
• Have you explained what your changes do? Performance claims (e.g. "this is faster") must include Hyperfine benchmarks.
• Have you explained why you'd like these changes included, not just what they do?
• For bug fixes, have you given step-by-step brew commands to reproduce the bug?
• Have you written new tests (excluding integration tests)? Here's an example.
• Have you successfully run brew lgtm (style, typechecking and tests) locally?

---

• AI was used to generate or assist with generating this PR.

---

[Copilot]

Pull request overview

This PR updates Homebrew documentation to prevent Jekyll/Liquid from interpreting literal {{...}} brace tokens as Liquid output, and removes an outdated “test error” troubleshooting section referencing old Linuxbrew-era behavior and a decommissioned Ubuntu wiki page.

Changes:

• Removed the “Common build failures → Test errors” section from the homebrew-core maintainer guide.
• Wrapped paragraphs/lists containing literal {{...}} tokens in {% raw %}…{% endraw %} blocks in the Formula and Cask cookbooks to ensure the tokens render verbatim on the docs site.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
docs/Homebrew-homebrew-core-Maintainer-Guide.md	Removes an outdated troubleshooting subsection (including a legacy external link).
docs/Formula-Cookbook.md	Adds {% raw %} / {% endraw %} to prevent Liquid from processing documented {{...}} tokens.
docs/Cask-Cookbook.md	Adds {% raw %} / {% endraw %} around a list that includes documented {{...}} tokens.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[Copilot]

Pull request overview

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

[MikeMcQuaid]

Thanks again!