merge: DOCS-686 (with edits)

Author: Sam Kleinman

source/aggregation.txt

@@ -19,6 +19,7 @@ full documentation of the aggregation framework here:
    applications/aggregation
    tutorial/aggregation-examples
    reference/aggregation
+   applications/map-reduce
 
 In addition to the aggregation framework, MongoDB provides simple
 :doc:`aggregation methods and commands </reference/simple-aggregation>`, 

source/applications.txt

@@ -41,6 +41,7 @@ The following documents outline basic application development topics:
    - :doc:`/applications/indexes`
    - :doc:`/applications/aggregation`
    - :doc:`/reference/connection-string`
+   - :doc:`/applications/map-reduce`
 
 .. _application-patterns: