Autoformat changelogs (#62650)

Add configuration to autoformat the root changelog.txt file as markdown.
It's authored with markdown syntax but the .txt extension prevents autoformatting.

Apply autoformatting to markdown files:

```sh
npm run format -- changelog.txt "packages/*/CHANGELOG.md"
```

Add a `linguist-language=Markdown` git attribute to changelog.txt so that GitHub treats it as markdown.

---

Co-authored-by: sirreal <[email protected]>
Co-authored-by: ellatrix <[email protected]>

Author: sirreal

.gitattributes

@@ -14,3 +14,6 @@
 
 # Directories with vendored code.
 packages/edit-site/lib/** linguist-vendored
+
+# The changelog.txt file is authored as markdown.
+changelog.txt linguist-language=Markdown

.prettierrc.js

@@ -1,3 +1,11 @@
 // Import the default config file and expose it in the project root.
 // Useful for editor integrations.
-module.exports = require( '@wordpress/prettier-config' );
+module.exports = {
+	...require( '@wordpress/prettier-config' ),
+	overrides: [
+		{
+			files: [ 'changelog.txt' ],
+			options: { parser: 'markdown' },
+		},
+	],
+};

changelog.txt

@@ -17,7 +17,7 @@
 
 ### Bug Fixes
 
--	Fix null and number strings as namespaces runtime error. ([#61960](https://github.com/WordPress/gutenberg/pull/61960/))
+-   Fix null and number strings as namespaces runtime error. ([#61960](https://github.com/WordPress/gutenberg/pull/61960/))
 
 ## 5.7.0 (2024-05-16)
 

packages/interactivity/CHANGELOG.md

@@ -10,9 +10,11 @@ For each user feature we should also add a importance categorization label  to i
 -->
 
 ## Unreleased
+
 -   [*] Bump Aztec-Android version to v1.5.1 [#36861]
 -   [*] Add text input state to Aztec view [#40480]
 
 ## 1.50.0
+
 -   [*] Block split/merge fix for a (never shipped) regression (Android only) [#29683]
--   [***] Bump minimum deployment target to iOS 13.0 [#27577]
+-   [***] Bump minimum deployment target to iOS 13.0 [#27577]