chore: Port FreeSewing.dev to docusaurus

The replaces the NextJS site powering FreeSewing.dev with a Docusaurus
setup. It's part of my efforts to simplify FreeSewing's setup so we can
focus on our core value proposition.

sites/dev/docs/reference/api/utils/capitalize/readme.mdx

@@ -0,0 +1,19 @@
+---
+title: utils.capitalize()
+---
+
+The `utils.capitalize()` function returns the string you pass it with its first
+letter turned into uppercase.
+
+## Signature
+
+```js
+String utils.capitalize(String input)
+```
+
+## Example
+
+```js
+capitalize('hello') // returns 'Hello')
+capitalize('hello there') // returns 'Hello there'
+```