Document process for freezing dependencies and freeze git dependencies

to commits

README.md

@@ -72,3 +72,24 @@ CFLAGS='-std=c99' pip install --no-cache --no-binary :all: cffi
 CFLAGS='-std=c99' pip install --no-cache --no-binary :all: cryptography
 ```
 
+## Update Requirements
+
+1. Create a new virtualenv 
+2. Activate new virtualenv
+3. Install unversioned dependencies 
+4. Run tests 
+5. Freeze requirements 
+6. Deactivate virtualenv 
+7. Remove virtualenv 
+
+Example (commands may differ dependending on virtualenv tools):
+
+```
+pyenv virtualenv 2.7.11 quay-deps
+pyenv activate quay-deps
+pip install -r requirements-nover.txt
+./local-test.sh
+pip freeze > requirements.txt
+pyenv deactivate quay-deps
+pyenv uninstall quay-deps
+```