Add gpg cache parameters

salt/files/master.d/f_defaults.conf

 #
 {{ get_config('pillar_cache_backend', 'disk') }}
 
+# A master can also cache GPG data locally to bypass the expense of having to render them
+# for each minion on every request. This feature should only be enabled in cases
+# where pillar rendering time is known to be unsatisfactory and any attendant security
+# concerns about storing decrypted GPG data in a master cache have been addressed.
+#
+# When enabling this feature, be certain to read through the additional ``gpg_cache_*``
+# configuration options to fully understand the tunable parameters and their implications.
+{{ get_config('gpg_cache', 'False') }}
+
+# If and only if a master has set ``gpg_cache: True``, the cache TTL controls the amount
+# of time, in seconds, before the cache is considered invalid by a master and a fresh
+# pillar is recompiled and stored.
+{{ get_config('gpg_cache_ttl', '86400') }}
+
+# If and only if a master has set `gpg_cache: True`, one of several storage providers
+# can be utilized. Available options are the same as ``pillar_cache_backend``.
+{{ get_config('gpg_cache_backend', 'disk') }}
 
 #####          Syndic settings       #####
 ##########################################