Add issue template, move PR template to .github

Closes: https://github.com/projectatomic/rpm-ostree/issues/673

Closes: #674
Approved by: cgwalters

.github/ISSUE_TEMPLATE

@@ -0,0 +1,28 @@
+** Host system details **
+
+Provide the output of `rpm-ostree status`.
+
+** Expected vs actual behavior **
+
+```
+# rpm-ostree install somepackage
+error: installing somepackage: encountered some an error
+```
+
+Expected:
+
+```
+# rpm-ostree install foo
+...
+Success!
+```
+
+**Steps to reproduce it**
+
+Provide any additional data that may help debug this - which specific version of
+an RPM is in the repo, or any host system configuration.
+
+**Would you like to work on the issue?**
+
+Please let us know if you can work on it or the issue should be assigned to
+someone else.