docs: Add RELEASE.md to document release process (#834)

Author: nicohrubec

RELEASE.md

@@ -0,0 +1,5 @@
+# Release Process
+
+1. Open a PR to update the changelog on `main`
+2. After the changelog PR is merged, go to the **Actions** tab and manually trigger the **"Prepare Release"** workflow, entering the version you want to release
+3. After the workflow completes, go to [getsentry/publish](https://github.com/getsentry/publish), find the corresponding issue created by the workflow, and add the `accepted` label to finalize the release