DOCS-1111 clarify sort operations with index

DOCS-1111 incorporate some code review feedback

DOCS-1111 clarify sort operations with index

Signed-off-by: Sam Kleinman <samk@10gen.com>
DOCS-1723 glossary edits - part 2

Signed-off-by: Sam Kleinman <samk@10gen.com>
DOCS-1492 split & splitChunk