Add comment to indicate duplicate regexes

This comment was added in mozilla-central and seems useful, adding it to keep m-c and github in sync.

Readability.js

@@ -112,8 +112,11 @@ Readability.prototype = {
   // All of the regular expressions in use within readability.
   // Defined up here so we don't instantiate them repeatedly in loops.
   REGEXPS: {
+    // NOTE: These two regular expressions are duplicated in
+    // Readability-readerable.js. Please keep both copies in sync.
     unlikelyCandidates: /-ad-|banner|breadcrumbs|combx|comment|community|cover-wrap|disqus|extra|foot|header|legends|menu|related|remark|replies|rss|shoutbox|sidebar|skyscraper|social|sponsor|supplemental|ad-break|agegate|pagination|pager|popup|yom-remote/i,
     okMaybeItsACandidate: /and|article|body|column|main|shadow/i,
+
     positive: /article|body|content|entry|hentry|h-entry|main|page|pagination|post|text|blog|story/i,
     negative: /hidden|^hid$| hid$| hid |^hid |banner|combx|comment|com-|contact|foot|footer|footnote|masthead|media|meta|outbrain|promo|related|scroll|share|shoutbox|sidebar|skyscraper|sponsor|shopping|tags|tool|widget/i,
     extraneous: /print|archive|comment|discuss|e[\-]?mail|share|reply|all|login|sign|single|utility/i,