Updated example config with notes on if_modified flag

src/zasd.conf.example.py

@@ -34,6 +34,12 @@ defaults = dict(
 
 # Whether to ignore triggers on filesystems whose files
 # have not been modifed since the trigger was last fired
+# Enabling this for a filesystem will cause an instance
+# of fswatch to launch for every ZFS filesystem. This
+# may use a lot of open file descriptors, so maybe avoid
+# if you have large filesystems with lots of folders.
+# Taking snapshots unconditionally is probably more
+# reliable.
 #    if_modified     = False,
 
 # Priority for snapshot; if more than one trigger fires