Fix confusing negative in contribution guidelines

Author: tpope

CONTRIBUTING.markdown

@@ -1,7 +1,7 @@
 Follow the commit message guidelines at [commit.style](https://commit.style).
-This is an absolute requirement for my repositories, and furthermore this
-proves you didn't actually read the contribution guidelines, which doesn't
-make for a great first impression.
+This is an absolute requirement for my repositories, and doing so proves you
+actually read the contribution guidelines, which makes for a good first
+impression.
 
 Good commit messages imply good commits.  Pull requests should typically be a
 single commit, or for the rare complicated case, a series of atomic commits.