Adding activation of Virtual env in Python (#158)

* Update README.md

README.md

@@ -114,7 +114,8 @@ You'll need Python 3, Google Chrome and chromedriver (`brew install chromedriver
 installed to run this:
 
  1. `python3 -m venv .venv`
- 2. `pip install -r requirements.txt`
- 3. `python upload_parrots.py --team YOUR_TEAM --username YOUR_EMAIL --password YOUR_PASS`
+ 1. `source .venv/bin/activate` on Mac or `.venv\Scripts\activate` on Windows
+ 1. `pip install -r requirements.txt`
+ 1. `python upload_parrots.py --team YOUR_TEAM --username YOUR_EMAIL --password YOUR_PASS`
 
  __Notice__: The uploader won't re-write already existing parrots if they match by name.