Readme updates

Author: Jeff Schroeder

README.md

@@ -9,16 +9,21 @@ A Python library to retrieve data from Pyth account structures off the Solana bl
 Developer Setup
 ---------------
 
+Using python 3.7 or newer, create, and activate a virtual environment:
+
+    python3 -m venv ve
+    . ve/bin/activate
+
 To install this library in editable mode with test dependencies:
 
     pip install -e '.[testing]'
 
 To run the unit tests:
 
-    pytest --cov=pythclient
+    pytest
 
 If html based test coverage is more your jam:
 
-    pytest --cov-report=html --cov=pythclient
+    pytest --cov-report=html
 
 The coverage webpages will be in the `htmlcov` directory.