Move issue/pull request templates to .github folder and split up

* Now that we have a .github folder we can have separate templates for bug
  reports and feature requests.

.github/pull_request_template.md

@@ -0,0 +1,19 @@
+<!--
+Before submitting a pull request you are strongly recommended to read the
+docs/CONTRIBUTING.md file which gives some information on how to prepare a
+change:
+
+https://github.com/baldurk/renderdoc/blob/v1.x/docs/CONTRIBUTING.md
+
+For small changes you don't have to read the document end to end, but should at
+least look at the sections on how to ensure your code and commits are formatted
+according to the style requirements.
+-->
+
+## Description
+
+<!--
+Describe here what your pull request changes and why it should happen. For small
+changes which are obvious this can just be a line or two - even the commit
+message is sometimes enough.
+-->