DOCS-4398: clarifies authenticationDatabase description

- --authenticationDatabase is required for mongotop and mongostat
  when connecting to a mongod or mongos that uses auth

Signed-off-by: Sam Kleinman <samk@10gen.com>

Author: schmalliso

source/includes/options-mongostat.yaml

@@ -112,6 +112,9 @@ inherit:
   name: authenticationDatabase
   program: _shared
   file: options-shared.yaml
+post: |
+  {{role}} is required for :program:`mongod`
+  and :program:`mongos` instances that use :ref:`authentication`.
 ---
 program: mongostat
 name: authenticationMechanism

source/includes/options-mongotop.yaml

@@ -120,6 +120,9 @@ inherit:
   name: authenticationDatabase
   program: _shared
   file: options-shared.yaml
+post: |
+  {{role}} is required for :program:`mongod`
+  and :program:`mongos` instances that use :ref:`authentication`.
 ---
 program: mongotop
 name: authenticationMechanism

source/includes/options-shared.yaml

@@ -247,15 +247,10 @@ program: _shared
 name: authenticationDatabase
 args: <dbname>
 directive: option
-pre: | 
+description: | 
   .. versionadded:: 2.4
 
   Specifies the database that holds the user's credentials.   
-description: |
-  If you do not
-  specify an authentication database, {{program}} assumes that the
-  database specified as the argument to {{role}} holds
-  the user's credentials.
 optional: true
 ---
 program: _shared