DOCS-990 bounds parameter in movechunk, doc'd splitchunk as well

note that splitChunk does not support bounds AFAICT
incorporate Sam's comments from codereview

Updated with changes from samk, greg
DOCS-990 fix merge conflicts

Conflicts:
	source/reference/command/moveChunk.txt
	source/reference/command/split.txt
	source/reference/method/sh.moveChunk.txt