add releasing instructions

Author: skullface

README.md

@@ -21,4 +21,17 @@ $ npm install --save-dev prettier prettier-plugin-tailwindcss @planetscale/core-
 
 ```
 
-[Read more on sharing configurations.](https://prettier.io/docs/en/configuration.html#sharing-configurations)
+[Read more on sharing configurations](https://prettier.io/docs/en/configuration.html#sharing-configurations).
+
+## Releasing
+
+Create a [Personal Access Token (classic)](https://github.com/settings/tokens) with the `write:package` scope and log into npm with that token [(per GitHub docs)](https://docs.github.com/en/packages/working-with-a-github-packages-registry/working-with-the-npm-registry#authenticating-with-a-personal-access-token):
+
+```shell
+$ npm login --scope=@NAMESPACE --auth-type=legacy --registry=https://npm.pkg.github.com
+
+> Username: USERNAME
+> Password: TOKEN
+```
+
+Run the `postpublish` script with `$ npm run postpublish`.