Update readme

Author: Faustasm

README.md

@@ -233,7 +233,7 @@ Set up environment and install dependencies:
 # run at project root, python3 and virtualenv must be installed
 virtualenv ENV
 source ENV/bin/activate
-pip install -r requirements.txt or pip install -r requirements-dev.txt if changes to the api need to be made
+pip install -r requirements.txt && pip install -r requirements-dev.txt
 ```
 
 Install the package in editable mode, as mentioned in