Sentence case all example titles (#2889)

This PR converts all example titles and categories to sentence case, to
make them consistent with our UI and the other examples.

### Change Type

- [x] `documentation` — Changes to the documentation only[^2]

[^1]: publishes a `patch` release, for devDependencies use `internal`
[^2]: will not publish a new version

### Test Plan

1. Look at the examples app.
2. Check that all the titles of examples make you feel calm and good
inside.

- [ ] Unit Tests
- [ ] End to end tests

### Release Notes

- Docs: Made the examples titles sentence case.

apps/docs/scripts/functions/generateExamplesContent.ts

@@ -9,7 +9,7 @@ const section: InputSection = {
 	description: 'Code recipes for bending tldraw to your will.',
 	categories: [
 		{ id: 'basic', title: 'Getting Started', description: '', groups: [] },
-		{ id: 'ui', title: 'UI/Theming', description: '', groups: [] },
+		{ id: 'ui', title: 'UI & Theming', description: '', groups: [] },
 		{ id: 'shapes/tools', title: 'Shapes & Tools', description: '', groups: [] },
 		{ id: 'data/assets', title: 'Data & Assets', description: '', groups: [] },
 		{ id: 'editor-api', title: 'Editor API', description: '', groups: [] },