replace greedy !**/node_modules/** pattern and added note about similar folders to be ignored

* replace greedy !**/node_modules/** pattern with light one—!node_modules
* add note about need to add git, bower and similar folders to ignored patterns list

I improved this text in README because in my project i have 3 node_modules folder, one bower folder and git folder. When I use greedy pattern like this `!**/node_modules/••` gaze lib get 20000 files in raw in every watch loop and only 1/20 part get into addToWatched list — which is inefficient and very annoying, cause of one or two minutes delays