fix: pip -e and -t don't get along well

https://stackoverflow.com/questions/38862228/why-cant-i-call-pip-with-target-and-editable

.github/CONTRIBUTING.md

@@ -28,13 +28,11 @@ If you use VS code, installing [nf-core extension pack](https://marketplace.visu
 
 ## Installation
 
-For testing and debugging, We recommend installing the dev version of champagne in editable mode to a user-specific location.
+For testing and debugging, We recommend installing the dev version of champagne to a user-specific location.
 
 ```
 git clone https://github.com/CCBR/CHAMPAGNE
 mkdir -p ~/bin/champagne
-pip install -e CHAMPAGNE -t ~/bin/champagne
+pip install ./CHAMPAGNE -t ~/bin/champagne
 export PATH="$HOME/bin/champagne/bin:$PATH"
 ```
-
-Then you can run your local version of champagne, make edits to the code as needed, and run your edited version again without reinstalling it.