Re-add pull-request template

[hkirsman]

I noticed during refactoring pull request template was removed https://github.com/wunderio/wunder-theme-base/pull/9/files#diff-b2496e80299b8c3150b1944450bd81c622e04e13d15c411d291db0927d75fd6b It should still be here if this project we work on.

@DavisAre

[Outim]

I added this in a PR: #14 :)