Improve documents of SyntaxHighlightFilter

Author: JuanitoFatas

lib/html/pipeline/syntax_highlight_filter.rb

@@ -4,8 +4,15 @@
 
 module HTML
   class Pipeline
-    # HTML Filter that syntax highlights code blocks wrapped
-    # in <pre lang="...">.
+    # HTML Filter that syntax highlights text inside code blocks.
+    #
+    # Context options:
+    #
+    #   :highlight => String represents the language to pick lexer. Defaults to empty string.
+    #   :scope => String represents the class attribute adds to pre element after.
+    #             Defaults to "highlight highlight-css" if highlights a css code block.
+    #
+    # This filter does not write any additional information to the context hash.
     class SyntaxHighlightFilter < Filter
       def initialize(*args)
         super(*args)