DOCS-829 incorporated eric's comments

Author: kay-kim

source/applications/map-reduce.txt

@@ -226,21 +226,21 @@ The map-reduce operation is composed of many tasks, including:
 
 These various tasks take the following locks:
 
-- The reads from the input collection takes a read lock that is yielded
-  every 100 documents.
+- The read phase takes a read lock.  It yields every 100 documents.
 
 - The JavaScript code (i.e. ``map``, ``reduce``, ``finalize``
   functions) is executed in a single thread, taking a JavaScript lock;
   however, most JavaScript tasks in map-reduce are very short and
-  yields the lock frequently.
+  yield the lock frequently.
 
 - The insert into the temporary collection takes a write lock for a
   single write.
 
-  If the final collection does not exist, the creation of the final
-  collection the output actions takes a write lock. If the final
-  collection exists, then the output actions (i.e. ``merge``,
-  ``replace``, ``reduce``) take a write lock.
+  If the output collection does not exist, the creation of the output
+  collection takes a write lock.
+
+  If the output collection exists, then the output actions (i.e.
+  ``merge``, ``replace``, ``reduce``) take a write lock.
 
 Although single-threaded, the map-reduce tasks interleave and appear to
 run in parallel.