chore: stub out basic READMEs for all packages

packages/richtext-slate/README.md

@@ -0,0 +1,28 @@
+# Payload Slate Rich Text Editor
+
+Slate Rich Text Editor for [Payload](https://payloadcms.com).
+
+- [Main Repository](https://github.com/payloadcms/payload)
+- [Payload Docs](https://payloadcms.com/docs)
+
+## Installation
+
+```bash
+npm install @payloadcms/richtext-slate
+```
+
+## Usage
+
+```ts
+import { buildConfig } from 'payload/config'
+import { slateEditor } from '@payloadcms/richtext-slate'
+
+export default buildConfig({
+  editor: slateEditor({})
+  // ...rest of config
+})
+
+```
+
+More detailed usage can be found in the [Payload Docs](https://payloadcms.com/docs/configuration/overview).
+