Add release instructions to README (#123)

* Add release instructions to README

* Also update CHANGELOG, MIGRATION and the github workflows

* Also update the api_compatibility value

Author: rnestler

README.md

@@ -4,3 +4,19 @@
 ![Validate formatting](https://github.com/SpaceApi/schema/workflows/Validate%20formatting/badge.svg?event=push)
 
 These are [JSON Schema](https://json-schema.org/) files for the SpaceAPI.
+
+## Releasing a new version
+
+ * Make sure the `CHANGELOG.md` is up to date
+ * Update `MIGRATION.md` with upgrade instructions
+ * Rename the current `xx-draft.json` to `xx.json` and create `xx+1-draft.json`
+   * Replace the `"$id"` field accordingly
+   * Replace the `"description"` field accordingly
+   * Replace the `"properties"."api_compatibility"."contains"."const"` accordingly
+   * Update the `.github/workflows` accordingly
+ * Update the website
+   * Regenerate the schema docs
+   * Update the example
+ * Update the validator
+   * Update the schema in https://github.com/spaceapi-community/go-spaceapi-validator and release a new version
+   * Update the go-spaceapi-validator version in https://github.com/SpaceApi/validator/