DOCS-10737: updated 3.6 release notes

Author: steveren

source/release-notes/3.6.txt

@@ -366,10 +366,15 @@ MongoDB 3.6 includes the following enhancements:
 - :dbcommand:`dropDatabase` waits until all collections drops in the
   database have propagated to a majority of the replica set members.
 
-
 - The new :query:`$jsonSchema` operator matches documents that validate 
   against the given JSON Schema.
 
+- The new :parameter:`honorSystemUmask` startup option for
+  :program:`mongod` causes new files created by MongoDB to have
+  the read/write permissions specified by the `umask
+  <https://en.wikipedia.org/wiki/Umask>`_ of the user who runs the
+  :program:`mongod` process. Only available on Linux and OS X systems.
+
 Changes Affecting Compatibility
 -------------------------------