document before/after

@splattael 
also using this pattern in test/around_spec.rb so it works :)

On Mon, Nov 10, 2014 at 2:07 AM, Peter Suschlik <notifications@github.com>
wrote:

> In README.md:
>
> > @@ -48,7 +48,7 @@ require 'tmpdir'
> >  describe "inside new directory" do
> >    around do |test|
> >      Dir.mktmpdir do |dir|
> > -      $dir = dir
> > +      @dir = dir
> >        Dir.chdir(dir) do
>
> @grosser <https://github.com/grosser> Are you sure about the scope of @dir
> <https://github.com/dir>? Is it visible inside it block?
>
> —
> Reply to this email directly or view it on GitHub
> <https://github.com/splattael/minitest-around/pull/25/files#r20073806>.
>