Simplify the README - Move extra details to an "advanced user" section

[nunoguedelha]

This is a follow-up of #26 (review).

@traversaro wrote:

The README contains already a lot of documentation that can confuse users that are just interested in using the library. Probably after robotology/robotology-superbuild#576 we could move this "advanced" docs for people that want to modify matlab-whole-body-simulator in separate page, and just leave in the README the easy way of installing it?

@nuno wrote:

Yes absolutely, makes sense. In any case I would say that the steps 1-2-3 listed in the MATLAB Online section stay the same after robotology/robotology-superbuild#576 is integrated. What changes is the content of the installer script. Then, the explanation on the bash limitations, along with the full sections "Installing from superbuild source" and "Installing from Robotology Conda channel" could be moved to the advanced docs as you mentioned.

[nunoguedelha]

Implemented in #49 .