adding commentary tag to posts with commentary

BUR #258 has been rejected.

mass update has:commentary -commentary -> commentary

Lots of posts have commentary but no commentary tag.

First things first:

• Commentary is a tag for when the commentary is completely understandable in English, and there is some actual commentary
• has:commentary is when there is at least 1 character written in the commentary

Now, the scenarios where they are not the same:

• Hashtag-only commentaries. This should not have any commentary tags
• Commentaries that are not understandable in English. This is when the tag should be commentary_request instead.

The bulk update request #258 (forum #1792) has been rejected by @Lyren.