feat(markdown): add markdown

README.md

@@ -3,3 +3,37 @@
 ```sh
 pnpm install https://git.methanium.net/methanium/ui/releases/download/latest/methanium-ui.tgz
 ```
+
+## Markdown
+
+The renderer is available from the package root. The live editor, compact text
+renderer, and emoji APIs use the `@methanium/ui/markdown` entry point.
+
+```tsx
+import { Markdown } from "@methanium/ui";
+import {
+  EmojiProvider,
+  Input,
+  createEmojiRegistry,
+} from "@methanium/ui/markdown";
+
+const registry = createEmojiRegistry({
+  customEmojis: [
+    {
+      shortcode: ":party_parrot:",
+      aliases: [":parrot_party:"],
+      src: "/emoji/party-parrot.webp",
+    },
+  ],
+});
+
+<EmojiProvider registry={registry}>
+  <Input value={value} setValue={setValue} />
+  <Markdown content={value} />
+</EmojiProvider>;
+```
+
+Custom shortcodes and aliases must be unique and may not collide with built-in
+Twemoji names. Twemoji graphics are bundled locally and do not use a CDN. The
+graphics are provided by the [Twemoji project](https://github.com/jdecked/twemoji)
+under CC-BY 4.0; code is licensed under MIT.