Merge pull request aws#133 from ca-nguyen/update-contributing

documentation: Updated git checkout command and reorder unit test steps

Author: ca-nguyen

CONTRIBUTING.md

@@ -57,8 +57,8 @@ Before sending us a pull request, please ensure that:
 ### Running the Unit Tests
 
 1. Install tox using `pip install tox`
-1. Install test dependencies, including coverage, using `pip install .[test]`
 1. cd into the aws-step-functions-data-science-sdk-python folder: `cd aws-step-functions-data-science-sdk-python` or `cd /environment/aws-step-functions-data-science-sdk-python`
+1. Install test dependencies, including coverage, using `pip install ".[test]"`
 1. Run the following tox command and verify that all code checks and unit tests pass: `tox tests/unit`
 
 You can also run a single test with the following command: `tox -e py36 -- -s -vv <path_to_file><file_name>::<test_function_name>` 
@@ -80,7 +80,7 @@ You should only worry about manually running any new integration tests that you
 
 1. Create a new git branch:
  ```shell
- git checkout -b my-fix-branch master
+ git checkout -b my-fix-branch
  ```
 1. Make your changes, **including unit tests** and, if appropriate, integration tests.
  1. Include unit tests when you contribute new features or make bug fixes, as they help to: