add pull-request template

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

.github/PULL_REQUEST_TEMPLATE.md

@@ -0,0 +1,30 @@
+<!--
+Please make sure you've read and understood our contributing guidelines;
+https://github.com/docker/cli/blob/master/CONTRIBUTING.md
+
+** Make sure all your commits include a signature generated with `git commit -s` **
+
+For additional information on our contributing process, read our contributing
+guide https://docs.docker.com/opensource/code/
+
+If this is a bug fix, make sure your description includes "fixes #xxxx", or
+"closes #xxxx"
+
+Please provide the following information:
+-->
+
+**- What I did**
+
+**- How I did it**
+
+**- How to verify it**
+
+**- Description for the changelog**
+<!--
+Write a short (one line) summary that describes the changes in this
+pull request for inclusion in the changelog:
+-->
+
+
+**- A picture of a cute animal (not mandatory but encouraged)**
+