docs: add publishing instructions to the contributing README

CONTRIBUTING.md

@@ -49,3 +49,26 @@ module "example" {
   source = "git::https://github.com/<USERNAME>/<REPO>.git//<MODULE-NAME>?ref=<BRANCH-NAME>"
 }
 ```
+
+## Releases
+
+> [!WARNING]
+> Version numbers are very important for publishing to Terraform. If the version number is incorrect in any way, there is a risk that some modules could stop working.
+
+Much of our release process is automated. To cut a new release:
+
+1. Navigate to [GitHub's Releases page](https://github.com/coder/modules/releases)
+2. Click "Draft a new release"
+3. Click the "Choose a tag" button and type a new release number in the format `v<major>.<minor>.<patch>` (e.g., `v1.18.0`). Then click "Create new tag".
+4. Click the "Generate release notes" button, and clean up the resulting README. Be sure to clean up any notes that would not be relevant to end-users (e.g., bumping dependencies).
+5. Once everything looks good, click the "Publish release" button.
+
+Once the release has been cut, a script will run to check whether there are any modules that will require that the new release number be published to Terraform. If there are any, a new pull request will automatically be generated. Be sure to approve this PR and merge it into the `main` branch.
+
+Following that, our automated processes will handle publishing new data for [`registry.coder.com`](https://github.com/coder/registry.coder.com/):
+
+1. Publishing new versions to Coder's [Terraform Registry](https://registry.terraform.io/providers/coder/coder/latest)
+2. Publishing new data to the [Coder Registry](https://registry.coder.com)
+
+> [!NOTE]
+> Some data in `registry.coder.com` is fetched on demand from the Module repo's main branch. As such, some changes will be made almost immediately, while others may require some time.