[dx] Allow vscode to search inside md files by default (#3105)

Before this PR all .md files were targeted by the `.ignore` file, which
has bitten me on a number of occasions since .md files often contain
valuable information (e.g. the vscode extensions docs). This PR
unignores .md files while still ignoring _generated_ .md files like our
changelogs, the api-report files, and the generated docs sections.

Additionally, the `yarn format` and `yarn lint` commands were configured
slightly differently, which was confusing, so I've unified those and
simplified the lint.ts script at the same time.

### Change Type

- [ ] `patch` — Bug fix
- [ ] `minor` — New feature
- [ ] `major` — Breaking change
- [ ] `dependencies` — Changes to package dependencies[^1]
- [ ] `documentation` — Changes to the documentation only[^2]
- [ ] `tests` — Changes to any test code only[^2]
- [x] `internal` — Any other changes that don't affect the published
package[^2]
- [ ] I don't know

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

templates/nextjs/next.config.cjs

@@ -1,8 +1,8 @@
 /** @type {import('next').NextConfig} */
 const nextConfig = {
-  experimental: {
-    serverComponentsExternalPackages: ["@tldraw/tldraw"],
-  },
-};
+	experimental: {
+		serverComponentsExternalPackages: ['@tldraw/tldraw'],
+	},
+}
 
-module.exports = nextConfig;
+module.exports = nextConfig