Adding config defaults and hints to ob.cfg

Author: jonathancross

ob.cfg

@@ -1,4 +1,11 @@
 [CONSTANTS]
+
+# DATA_FOLDER Defaults:
+#   - Windows: C:\Users\[Username]\AppData\Roaming\openbazaar\
+#   - OSX:     /Users/[Username]/Library/Application Support/OpenBazaar/
+#   - Linux:   ~/.openbazaar/
+#
+# Uncomment this to customize (note: you cannot use ~. Instead use full path.):
 #DATA_FOLDER = /path/to/OpenBazaar/
 
 KSIZE = 20