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/mergeoptions/readme.mdx

@@ -0,0 +1,30 @@
+---
+title: utils.mergeOptions()
+---
+
+The `utils.mergeOptions()` function merges the user-provided options with the
+options from the pattern configuration.
+
+## Signature
+
+```js
+Object utils.mergeOptions(
+  Object settings,
+  Object optionsConfig
+)
+```
+
+## Notes
+
+Typically the only options that are passed as part of settings to the pattern
+are those that differ from the defaults.  This means that if you want to check
+an option outside a draft method, you need to check whether the option is set,
+and if it's not get the default value from the pattern config. Furthermore,
+where the default is stored and whether or not it should be further transformed
+depends on the option type.
+
+This function exists to facilitate this. You pass it the user-provided settings,
+and the pattern config options key, and it will return an object where all
+options are populated with the user-provided values, or their defaults if the
+user did not provide any input.
+