Add tip: wrapper utility

[tomjbradley]

You should add a tip for a simple wrapper/container utility. For example:

.wrapper {
  margin-right: auto;
  margin-left:  auto;
  max-width: 960px;
  padding-right: 10px;
  padding-left:  10px;
}

It's explained more in this css-tricks article.

I'd be happy to add it if you want.

[tomjbradley]

Hey, I was wondering should I submit a PR for this or do you not want the changes otherwise I'll just close the issue.

[AllThingsSmitty]

Feel free to submit a PR if you like, I haven't given this idea much thought yet.