Fix typo in help printout

[MBAustin]

"Th first matching" -> "The first matching"

[kfogel]

Hey, @MBAustin. I don't know if @geekless is actively maintaining his version here, but I merged all of the changes from his repository, as well as your pull request, into https://github.com/kfogel/wmctrl (which also incorporates the changes from @dancor's copy). My repository also includes the full release history of wmctrl, as one commit per version. In other words, it starts with a full history of the releases, then cherry-picked all of @dancor's and @geekless's commits onto that, then cherry-picked your typo fix, and also a few fixes from me for compiler warnings.

So in some sense it's the "most canonical" version-controlled copy of wmctrl now; at least, that's what I intended it to be.