Add a github issue template.

When a new issue is opened, request that the reporter leave
a description, and a reproducer for the issue.

Author: werwty

.github/ISSUE_TEMPLATE/bug-report.md

@@ -0,0 +1,21 @@
+---
+name: Bug report
+about: Let us know if something is broken on Mesa
+
+---
+
+**Describe the bug**
+<!-- A clear and concise description the bug -->
+
+**Expected behavior**
+<!-- A clear and concise description of what you expected to happen -->
+
+**To Reproduce**
+<!-- Steps to reproduce the bug, or a link to a project where the bug is visible -->
+
+**Additional context**
+<!--
+    Add any other context here.
+    Any details about your specific platform:
+    * If the problem is in the browser, what browser, version, and OS?
+-->

.github/ISSUE_TEMPLATE/feature-request.md

@@ -0,0 +1,14 @@
+---
+name: Feature request
+about: Suggest a new feature for Mesa
+
+---
+
+**What's the problem this feature will solve?**
+<!-- A clear and concise description of what the problem is. -->
+
+**Describe the solution you'd like**
+<!-- A clear and concise description of what you want to happen. -->
+
+**Additional context**
+<!-- Add any other context, links, etc. about the feature here. -->