add pruning variable

Author: chuckp22

backup.config-example

@@ -9,12 +9,13 @@ GHE_HOSTNAME="github.example.com"
 # elsewhere for backing up to a separate partition / mount point.
 GHE_DATA_DIR="data"
 
-# The number of backup snapshots to retain. Old snapshots are pruned after each
-# successful ghe-backup run. This option should be tuned based on the frequency
+# The number of backup snapshots to retain. Old snapshots are to be pruned separately 
+# after successful backups. This option should be tuned based on the frequency
 # of scheduled backup runs. If backups are scheduled hourly, snapshots will be
 # available for the past N hours; if backups are scheduled daily, snapshots will
-# be available for the past N days ...
+# be available for the past N days. Pruning enablement defaults to 'yes'
 GHE_NUM_SNAPSHOTS=10
+#GHE_PRUNING_ENABLED=no
 
 # The hostname of the GitHub appliance to restore. If you've set up a separate
 # GitHub appliance to act as a standby for recovery, specify its IP or hostname
@@ -97,4 +98,4 @@ GHE_NUM_SNAPSHOTS=10
 #EXTERNAL_DATABASE_RESTORE_SCRIPT="/bin/false"
 
 # If set to 'yes', Pages data will be included in backup and restore. Defaults to 'yes'
-#GHE_BACKUP_PAGES=no
+#GHE_BACKUP_PAGES=no