DOCS-924 adding ulimit and rewording question

Author: Sam Kleinman

source/administration/ulimit.txt

@@ -12,6 +12,8 @@ developers, are too low for MongoDB and can cause a number of issues
 in the course of normal MongoDB operation. Generally, MongoDB should
 be the only user process on a system, to prevent resource contention.
 
+.. _system-resource-utilization:
+
 Resource Utilization
 --------------------
 
@@ -24,7 +26,8 @@ deployment and its use to determine ideal ``ulimit`` settings.
 Generally, all :program:`mongod` and :program:`mongos` instances, like
 other processes:
 
-- track each incoming connection with a file descriptor *and* a thread.
+- track each incoming connection with a file descriptor *and* a
+  thread.
 
 - track each internal thread or *pthread* as a system process.
 
@@ -45,6 +48,8 @@ processes, including :ref:`TTL collections <ttl-collections>`,
 replication, and replica set health checks, which may require a small
 number of additional resources.
 
+.. _mongos-connection-use information:
+
 ``mongos``
 ~~~~~~~~~~
 

source/faq/sharding.txt

@@ -190,8 +190,8 @@ Once these migrations are complete, you may delete these files.
 You can set :setting:`noMoveParanoia` to ``true`` to disable this
 behavior.
 
-How many connections does each ``mongos`` need?
------------------------------------------------
+How does ``mongos`` use connections?
+------------------------------------
 
 Each client maintains a connection to a :program:`mongos` instance.
 Each :program:`mongos` instance maintains a pool of connections to the