Change master in links to HEAD

Author: wooorm

readme.md

@@ -56,11 +56,11 @@ or change the tree, so there are no openings for
 
 *   [`nlcst-to-string`](https://github.com/syntax-tree/nlcst-to-string)
     — Get text content in nlcst
-*   [`hast-util-to-string`](https://github.com/wooorm/rehype-minify/tree/master/packages/hast-util-to-string)
+*   [`hast-util-to-string`](https://github.com/wooorm/rehype-minify/tree/HEAD/packages/hast-util-to-string)
     — Get text content in hast
 *   [`hast-util-to-text`](https://github.com/syntax-tree/hast-util-to-text)
     — Get text content in hast according to the `innerText` algorithm
-*   [`hast-util-from-string`](https://github.com/wooorm/rehype-minify/tree/master/packages/hast-util-from-string)
+*   [`hast-util-from-string`](https://github.com/wooorm/rehype-minify/tree/HEAD/packages/hast-util-from-string)
     — Set text content in hast
 
 ## Contribute
@@ -111,11 +111,11 @@ abide by its terms.
 
 [author]: https://wooorm.com
 
-[contributing]: https://github.com/syntax-tree/.github/blob/master/contributing.md
+[contributing]: https://github.com/syntax-tree/.github/blob/HEAD/contributing.md
 
-[support]: https://github.com/syntax-tree/.github/blob/master/support.md
+[support]: https://github.com/syntax-tree/.github/blob/HEAD/support.md
 
-[coc]: https://github.com/syntax-tree/.github/blob/master/code-of-conduct.md
+[coc]: https://github.com/syntax-tree/.github/blob/HEAD/code-of-conduct.md
 
 [mdast]: https://github.com/syntax-tree/mdast