cairo lib installation over pip3 fails on MacOS

[Daniel-Genkin]

I ran pip3 install -r requirements.txt but kept getting the following error

OSError: no library called "cairo-2" was found
no library called "cairo" was found
no library called "libcairo-2" was found
cannot load library 'libcairo.so.2': dlopen(libcairo.so.2, 2): image not found
cannot load library 'libcairo.2.dylib': dlopen(libcairo.2.dylib, 2): image not found
cannot load library 'libcairo-2.dll': dlopen(libcairo-2.dll, 2): image not found

I think we need to clarify in the readme the troubleshooting steps for those who get this (and other) installation issues

[JoeFurfaro]

@Daniel-Genkin my thoughts on this at the moment:

I think adding a troubleshooting section in the README was a great idea, and I think we should do that for other platforms too. However, I don't wanna focus too much on distribution yet after adding troubleshooting info because once we have a more solid language down where we are very happy with all the features, we can start working on a proper distribution method :) (i.e a cross-platform installer).

Great work :)