Code review comment for lp:~thumper/launchpad/descriptions-for-merge-proposals

I'm approving this, since I think it's small enough and changes can be done later.

However, I would like to start a discussion on how similar to bugs this should be. If you have comments and description, it would be good to be consistent with other parts of Launchpad. The commenting system in merge proposals are similar enough to bugs, so having them work the same way would be beneficial.