correct doc about default value of DJANGOCMS_SNIPPET_CACHE (#120)

Author: eagleoflqj

README.rst

@@ -82,7 +82,7 @@ to edit the snippet content. You can customize the
 If dynamic content is inserted (for example ``{% show_menu ... %}``), the plugin cache must be disabled,
 please set ``DJANGOCMS_SNIPPET_CACHE`` to ``False`` in your settings::
 
-    DJANGOCMS_SNIPPET_CACHE = False # default value is True
+    DJANGOCMS_SNIPPET_CACHE = False # default value is False
 
 Migration 0010 requires the use of a user in order to create versions for existing snippets (if djangocms_versioning is installed and enabled),
 a user can be chosen with the setting ``DJANGOCMS_SNIPPET_VERSIONING_MIGRATION_USER_ID``, the default is 1.