Update config template to reflect changes

Added more detailed information related to the subreddit_format option
to reflect changes in SubredditPage, and mark the subreddit_format
option as an experimental feature.

tuir/templates/tuir.cfg

@@ -65,14 +65,23 @@ hide_username = False
 ; look_and_feel = default
 ; look_and_feel = compact
 
-; The subreddit_format option defines the format of submissions in a Subreddit
-; page. If specified, this option will override whatever was set in
-; look_and_feel.  Multiple lines are supported, but lines after the first must
-; be indented.  Unfortunately, this means that this isn't capable of
-; interpreting leading spaces.
+; The subreddit_format option defines the format of submissions in a
+; SubredditPage. Some caveats:
+;
+; If specified, this option will override whatever was set in
+; look_and_feel.
+;
+; Lines after the first line must be intented for Python's config parser to
+; understand the option having multiple lines
+;
+; Attributes are assigned only to the text written from a format specifier.
+; Certain characters ("<>/{}[]()|_-~") are assigned the separator attribute,
+; but no extraneous text added by the user will have an attribute.
+;
+; This feature is experimental and bound to have bugs. If you find one, please
+; file a bug report at https://gitlab.com/ajak/tuir/issues
 ;
 ; List of valid format specifiers and what they evaluate to:
-;
 ; %i index
 ; %t title
 ; %s score