Added Instruction for some case,
Added Instruction for some case,

The instruction was not sufficent to make the robot work. 
I just wrote what I changed to make this work.

I think, it is also better to recommend everybody to install pyUarm using source file instead of pip install. I guess pip didn't update the recent code yet.

uArm-Developer/UArmForROS,uArm-Developer/UArmForROS