Add improved docs

Author: wooorm

readme.md

@@ -8,19 +8,60 @@
 [![Backers][backers-badge]][collective]
 [![Chat][chat-badge]][chat]
 
-[**hast**][hast] utility to get the rank (or depth, level) of headings.
+[hast][] utility to transform to get the rank (also known as depth or level) of
+headings.
 
-## Install
+## Contents
+
+*   [What is this?](#what-is-this)
+*   [When should I use this?](#when-should-i-use-this)
+*   [Install](#install)
+*   [Use](#use)
+*   [API](#api)
+    *   [`headingRank(node)`](#headingranknode)
+*   [Types](#types)
+*   [Compatibility](#compatibility)
+*   [Security](#security)
+*   [Related](#related)
+*   [Contribute](#contribute)
+*   [License](#license)
+
+## What is this?
+
+This package is a utility that lets you get the rank (`1..6`) of heading
+elements (`h1..h6`).
+
+## When should I use this?
+
+This utility is pretty niche, if you’re here you probably know what you’re
+looking for!
 
-This package is [ESM only](https://gist.github.com/sindresorhus/a39789f98801d908bbc7ff3ecc99d99c):
-Node 12+ is needed to use it and it must be `import`ed instead of `require`d.
+To change heading ranks, use
+[`hast-util-shift-heading`][hast-util-shift-heading].
 
-[npm][]:
+## Install
+
+This package is [ESM only][esm].
+In Node.js (version 12.20+, 14.14+, 16.0+, or 18.0+), install with [npm][]:
 
 ```sh
 npm install hast-util-heading-rank
 ```
 
+In Deno with [`esm.sh`][esmsh]:
+
+```js
+import {headingRank} from 'https://esm.sh/hast-util-heading-rank@2'
+```
+
+In browsers with [`esm.sh`][esmsh]:
+
+```html
+<script type="module">
+  import {headingRank} from 'https://esm.sh/hast-util-heading-rank@2?bundle'
+</script>
+```
+
 ## Use
 
 ```js
@@ -33,7 +74,7 @@ headingRank(h('h5', 'Alpha')) //=> 5
 
 ## API
 
-This package exports the following identifiers: `headingRank`.
+This package exports the identifier `headingRank`.
 There is no default export.
 
 ### `headingRank(node)`
@@ -42,11 +83,23 @@ Get the rank (`1` to `6`) of headings (`h1` to `h6`).
 
 ###### Parameters
 
-*   `node` ([`Node`][node]) — Node to check
+*   `node` ([`Node`][node]) — node to check
 
 ###### Returns
 
-`rank` (`number?`) — Rank of the heading, or `null` if not a heading.
+Rank of the heading or `null` if not a heading (`number?`).
+
+## Types
+
+This package is fully typed with [TypeScript][].
+It exports no additional types.
+
+## Compatibility
+
+Projects maintained by the unified collective are compatible with all maintained
+versions of Node.js.
+As of now, that is Node.js 12.20+, 14.14+, 16.0+, and 18.0+.
+Our projects sometimes work with older versions, but this is not guaranteed.
 
 ## Security
 
@@ -56,14 +109,14 @@ There are no openings for [cross-site scripting (XSS)][xss] attacks.
 ## Related
 
 *   [`hast-util-heading`](https://github.com/syntax-tree/hast-util-heading)
-    — check if a node is a heading element
+    — check if a node is heading content
 *   [`hast-util-shift-heading`](https://github.com/syntax-tree/hast-util-heading)
-    — utility to change heading rank
+    — change heading rank
 
 ## Contribute
 
-See [`contributing.md` in `syntax-tree/.github`][contributing] for ways to get
-started.
+See [`contributing.md`][contributing] in [`syntax-tree/.github`][health] for
+ways to get started.
 See [`support.md`][support] for ways to get help.
 
 This project has a [code of conduct][coc].
@@ -104,18 +157,28 @@ abide by its terms.
 
 [npm]: https://docs.npmjs.com/cli/install
 
+[esm]: https://gist.github.com/sindresorhus/a39789f98801d908bbc7ff3ecc99d99c
+
+[esmsh]: https://esm.sh
+
+[typescript]: https://www.typescriptlang.org
+
 [license]: license
 
 [author]: https://wooorm.com
 
-[contributing]: https://github.com/syntax-tree/.github/blob/HEAD/contributing.md
+[health]: https://github.com/syntax-tree/.github
+
+[contributing]: https://github.com/syntax-tree/.github/blob/main/contributing.md
 
-[support]: https://github.com/syntax-tree/.github/blob/HEAD/support.md
+[support]: https://github.com/syntax-tree/.github/blob/main/support.md
 
-[coc]: https://github.com/syntax-tree/.github/blob/HEAD/code-of-conduct.md
+[coc]: https://github.com/syntax-tree/.github/blob/main/code-of-conduct.md
 
 [hast]: https://github.com/syntax-tree/hast
 
 [node]: https://github.com/syntax-tree/hast#nodes
 
 [xss]: https://en.wikipedia.org/wiki/Cross-site_scripting
+
+[hast-util-shift-heading]: https://github.com/syntax-tree/hast-util-shift-heading