doc(releasing.md): add note to update the git submodule SHAs

after fixes are made

Fixes deis/workflow#186

Author: Aaron Schlesinger

src/contributing/releasing.md

@@ -77,7 +77,7 @@ should be manually tested by as many people as possible. Special attention shoul
 user experience, both from an operator and developer perspective.
 
 Our goal is to test with as many object storage and Kubernetes installation configurations as
-possible, to ensure there are no gaps in configuration or functionality. See below for a testing
+possible, to ensure there are no gaps in configuration or functionality. See below for a sample testing
 matrix.
 
 Object Storage / Kubernetes Install | Kube-Solo | Google Container Engine | AWS | Micro-Kube | Vagrant |
@@ -86,6 +86,11 @@ Default (Minio)                     |
 Google Cloud Storage                |
 Amazon S3                           |
 
+_Note_: If bugs are found and fixes are made, do the following:
+
+- Update the appropriate docker tag(s) in the `generate_params.toml` file
+- Run `make git-update` in the aforementioned `deis-workflow-group` repository
+
 # Step 4: Tag and push Docker images
 
 After everyone has tested and determined that there are no showstopping problems for this release,