grammatical and stylistic changes to readme

Just some suggestions.
wrap pair insertion and deletion in editor operations

Signed-off-by: Chris Granger <ibdknox@gmail.com>
Merge branch 'master' of https://github.com/celwell/LightTable into celwell-master

Conflicts:
	README.md
Merge branch 'master' of github.com:Kodowa/Light-Table-Playground