chore(doc): add documentation of release process (#769)

relates to STACKITTPR-200

README.md

@@ -222,6 +222,10 @@ If you encounter any issues or have suggestions for improvements, please open an
 
 Your contribution is welcome! For more details on how to contribute, refer to our [Contribution Guide](./CONTRIBUTION.md).
 
+## Release creation
+
+See the [release documentation](./RELEASE.md) for further information.
+
 ## License
 
 Apache 2.0

RELEASE.md

@@ -0,0 +1,28 @@
+# Release
+
+## Release cycle
+
+A release should be created at least every 2 weeks. 
+
+## Release creation
+
+> [!IMPORTANT]
+> Consider informing / syncing with the team before creating a new release.
+
+1. Check out latest main branch on your machine
+2. Create git tag: `git tag vX.X.X`
+3. Push the git tag: `git push origin --tags`
+4. The [release pipeline](https://github.com/stackitcloud/terraform-provider-stackit/actions/workflows/release.yaml) will build the release and publish it on GitHub
+5. Ensure the release was created properly using the 
+    - [GitHub releases page](https://github.com/stackitcloud/terraform-provider-stackit/releases)
+    - [Terraform registry](https://registry.terraform.io/providers/stackitcloud/stackit/latest)
+
+## Troubleshooting
+
+In case the release only shows up as a draft release in the Terraform registry, check the state of the registry update in the [settings](https://github.com/stackitcloud/terraform-provider-stackit/settings/hooks):
+
+- Select 'edit' for the terraform registry webhook (requires authentication)
+- Switch to the "recent deliveries" tab
+- Check the last release, it should have positive result value and no error indication
+
+If the delivery failed or complains that the release is a draft, try to temporariliy declare the release as a pre-release in GitHub and then revert it it immediately.