add releasing doc

Author: vincentsarago

RELEASING.md

@@ -0,0 +1,25 @@
+# Releasing
+
+This is a checklist for releasing a new version of **titiler-stacapi**.
+
+1. Create a release branch named `release/vX.Y.Z`, where `X.Y.Z` is the new version
+
+2. Make sure the [Changelog](CHANGES.md) is up to date with latest changes and release date set
+
+3. Run [`bump-my-version`](https://callowayproject.github.io/bump-my-version/) to update all titiler's module versions: 
+
+    ```
+    bump-my-version bump minor --new-version 0.20.0
+    ```
+
+4. Push your release branch, create a PR, and get approval
+
+5. Once the PR is merged, create a new (annotated, signed) tag on the appropriate commit. Name the tag `X.Y.Z`, and include `vX.Y.Z` as its annotation message
+
+    ```
+    git tag vX.Y.Z
+    ```
+
+6. Push your tag to Github, which will kick off the publishing workflow
+
+7. Create a [new release](https://github.com/developmentseed/titiler-stacapi/releases/new) targeting the new tag, and use the "Generate release notes" feature to populate the description. Publish the release and mark it as the latest