DOCS-11289: mongorestore and index key length limit

Author: kay-kim

source/reference/program/mongorestore.txt

@@ -19,14 +19,10 @@
 Synopsis
 --------
 
-The :binary:`~bin.mongorestore` program writes data from a binary database
-dump created by :binary:`~bin.mongodump` to a MongoDB instance.
-
-.. versionadded:: 3.0.0 :binary:`~bin.mongorestore` also accepts data to
-   restore via the standard input.
-
-:binary:`~bin.mongorestore` can write data to either :binary:`~bin.mongod` or
-:binary:`~bin.mongos` instances.
+The :binary:`~bin.mongorestore` program loads data from either a binary
+database dump created by :binary:`~bin.mongodump` or the standard input
+(starting in version 3.0.0) into a :binary:`~bin.mongod` or
+:binary:`~bin.mongos` instance.
 
 .. include:: /includes/extracts/require-cmd-line-mongorestore.rst
 
@@ -52,6 +48,20 @@ Rebuild Indexes
 :binary:`~bin.mongorestore` recreates indexes recorded by
 :binary:`~bin.mongodump`.
 
+.. note::
+
+   Starting in MongoDB 2.6, creating indexes will :ref:`error if an
+   index key in an existing document exceeds the limit
+   <2.6-index-key-length-incompatibility>`. See
+   :ref:`2.6-index-key-length-incompatibility` for more information and
+   solution.
+
+   If you have an existing data set that violates this limit but want
+   to resolve the index issue after restoring the data, you can disable
+   the default index key length validation on the target database by
+   setting the :program:`mongod` instance's
+   :parameter:`failIndexKeyTooLong` parameter to false.
+
 Version Compatibility
 ~~~~~~~~~~~~~~~~~~~~~