Updated installation README

Updated pip install to http after feedback from issue facebookresearch#8

README.md

@@ -2,9 +2,9 @@
 
 # Nevergrad - A gradient-free optimization platform
 
-`nevergrad` is a Python3 library. It can be installed with:
+`nevergrad` is a Python 3.6+ library. It can be installed with:
 ```
-pip install -e git+git@github.com:facebookresearch/nevergrad@master#egg=nevergrad
+pip3 install git+https://github.com/facebookresearch/nevergrad@master#egg=nevergrad
 ```
 Alternatively, you can clone the repository and run `python3 setup.py develop` from inside the repository folder.