Lint Markdown files, fix headings style

[its-miroma]

Linting

• Remove trailing whitespace
• Single newline at the end of each file
• Remove unnecessary quotes in frontmatters
• Use relative link for CONTRIBUTING.md
• Update sidebar_translations.json
• Increment headings one level at a time
• Remove punctuation from headings, except exclamation marks

Headings

• Use Title Case through https://www.titlecase.com/
• Questions are exempted

Other

• Capitalize various instances of "Java", "Loader", "Loom"
• Add custom heading link in codecs.md
• Avoid using emphasis for headings in effects.md
  • Side Effect: the auto-generated TOC now shows those two headings
• Change info box in potions.md (may fix #89)
• Add alt text to image in hud.md
• Avoid using invisible spaces for a line break in creating-particles.md
• Capitalize alt texts in custom.md

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[IMB11]

Maybe it's worth integrating a markdown lint action/tool - I didn't originally suggest one because to be frank they all suck. There isn't really any good linters out there that:

• Automatic fix markdown issues using a CLI command.
• Aren't annoying to configure and understand lint errors.

[its-miroma]

I personally use markdownlint by David Anson, which has a VS Code extension and a cli.

It works pretty well and supports custom rules; there probably are some for Title Case as well.

Its rules are pretty strict, I'd recommend disabling MD025 and MD026 (with punctuation: ".,;:。，；：").

[its-miroma]

There even is a GitHub Action, although I have to admit I'm not super familiar with that

[its-miroma]

I personally use markdownlint by David Anson, which has a VS Code extension and a cli.

There even is a GitHub Action, although I have to admit I'm not super familiar with that

Please review #101