document after_initialize

Author: gjtorikian

README.md

@@ -203,6 +203,8 @@ For more examples of customizing the sanitization process to include the tags yo
 
 `NodeFilters`s can operate either on HTML elements or text nodes using CSS selectors. Each `NodeFilter` must define a method named `selector` which provides an instance of `Selma::Selector`. If elements are being manipulated, `handle_element` must be defined, taking one argument, `element`; if text nodes are being manipulated, `handle_text_chunk` must be defined, taking one argument, `text_chunk`. `@config`, and `@result` are available to use, and any changes made to these ivars are passed on to the next filter.
 
+`NodeFilter` also has an optional method, `after_initialize`, which is run after the filter initializes. This can be useful in setting up a custom state for `result` to take advantage of.
+
 Here's an example `NodeFilter` that adds a base url to images that are root relative:
 
 ```ruby

lib/html_pipeline/node_filter/mention_filter.rb

@@ -63,7 +63,6 @@ def mentioned_logins_in(text, username_pattern = USERNAME_PATTERN)
 
       SELECTOR = Selma::Selector.new(match_text_within: "*", ignore_text_within: IGNORE_PARENTS)
 
-      # TODO: document this
       def after_initialize
         result[:mentioned_usernames] ||= []
       end

lib/html_pipeline/node_filter/team_mention_filter.rb

@@ -53,7 +53,6 @@ def mentioned_teams_in(text, team_pattern = TEAM_PATTERN)
 
       SELECTOR = Selma::Selector.new(match_text_within: "*", ignore_text_within: IGNORE_PARENTS)
 
-      # TODO: document this
       def after_initialize
         result[:mentioned_teams] = []
       end