DOCS-1147 and DOCS-1206 text search

DOCS-1206 ulimits

Add note to Keyword Search Tutorial to link to Text Search

DOCS-1147 text index sharded cluster and replica sets and reorg

draft of the text-search usage

fix information about hyphens and copy edits

added more info

DOCS-1147 text search
DOCS-1177: text search documentation merge