Update README.md.
Update README.md.

Removed obsolete instruction to add CSS watcher.

Change-Id: I0e0330f3ac923204e375eb68fc4802c19f09d62f

shahrzadmn/vaadin-grid,jforge/components,jforge/components,manolo/components,shahrzadmn/vaadin-grid,jforge/components,shahrzadmn/vaadin-grid,manolo/components,shahrzadmn/vaadin-grid,manolo/components