Update README Docker instructions. (#776)

README.rst

@@ -25,7 +25,7 @@ Then:
 
 Alternatively:
  + Run :code:`docker pull azuresdk/azure-cli-python:latest`
- + Run :code:`alias az='docker run --rm -v ~/.azure:/root/.azure azuresdk/azure-cli-python az'`
+ + Run :code:`alias az='docker run --rm -i -t -v ~/.azure:/root/.azure azuresdk/azure-cli-python az'`
  + Then run :code:`az` as normal. e.g. :code:`az account login`
 
 Usage