Create a template clients to write 'bug' issues

[Cleop]

As a client
I want a template to follow when I come across a bug
so that I know how to effectively communicate what I've found with the rest of the team.

Linked to #36

@nelsonic shared this example of a well documented bug: Polymer/polymer#5047

However it is pretty technical and may not make lots of sense to a PO. However, our existing bug issues aren't ideal examples either and perhaps we could improve upon our bug reporting by creating a template for how to correctly record a bug into an issue.