trivial

Signed-off-by: Sam Kleinman <samk@10gen.com>
minor: fix for DOCS-1903
infra: adding metadriver intersphinx
fixes for replica set deployment tutorials
minor: using intraspinx link
Extend 2.6 release notes for $out

Filling in details on when the collection appears and what we do when the output collection already exists.

Signed-off-by: Sam Kleinman <samk@10gen.com>
edits to aggregation $out behavior