Update docs from transaction flow refactor

RELEASING.md

@@ -8,16 +8,23 @@ Releasing checklist:
 
 (3) Checkout the `main` branch. This is the only releasable branch.
 
-(4) Create a tag for the release.
+(4) Create and push a release branch.
+
+```sh
+git checkout -b release-v0.12.0
+git push release-v0.12.0
+```
+
+(5) Create a tag for the release.
 
 ```sh
 git tag v0.12.0
 ```
 
-(5) Push the tag to the main repository, [triggering the CI and release process](https://github.com/OpenZeppelin/nile/blob/951cf2403aa58a9b58c3c1a793b51cd5c58cb56e/.github/workflows/ci.yml#L55).
+(6) Push the tag to the main repository, [triggering the CI and release process](https://github.com/OpenZeppelin/nile/blob/951cf2403aa58a9b58c3c1a793b51cd5c58cb56e/.github/workflows/ci.yml#L55).
 
 ```sh
 git push origin v0.12.0
 ```
 
-(6) Finally, go to the repo's [releases page](https://github.com/OpenZeppelin/nile/releases/) and [create a new one](https://github.com/OpenZeppelin/nile/releases/new) with the new tag and the `main` branch as target.
+(7) Finally, go to the repo's [releases page](https://github.com/OpenZeppelin/nile/releases/) and [create a new one](https://github.com/OpenZeppelin/nile/releases/new) with the new tag and the `main` branch as target.