Create CONTRIBUTORS.md

Closes flathub#199

CONTRIBUTORS.md

@@ -0,0 +1,16 @@
+### Submitting a new package
+
+If you are submitting a new package please read the [submission](https://github.com/flathub/flathub/wiki/Submission-Guidelines)
+and [review](https://github.com/flathub/flathub/wiki/Review-Guidelines) guidelines in the wiki.
+
+Also double-check that your PR is against the `new-pr` branch.
+
+### Reporting a bug on a package
+
+Please open bugs for packages on their respective repositories you can search for them here: https://github.com/flathub
+
+### Requesting a new package
+
+Please do not open issues requesting packages. As long as a package meets the guidelines above and works it will be
+generally be accepted. If you want to create a Flatpak see the [documentation](https://flatpak.readthedocs.io/en/latest/)
+or join ircs://chat.freenode.net/flatpak for help.