Add GitHub issue template, as we used to have before (#961)
Add GitHub issue template, as we used to have before (#961)

When we used to maintain separare NAPALM drivers, we had an issue template
looking like this:
https://github.com/napalm-automation/napalm-junos/commit/110fec4bc9c50da43701b5019ecd859cc3c35f54#diff-faa36bc26a21ed93c8de974753b71507.

I was looking today through the issues we currently have open, and
I found some of them a bit chaotic, and hard to understand the context
/ environment the user runs. Additionally, some, e.g., #960, is really
hard to follow, and I've included a note to invite the user to check the
HitGub markdown manual.
spotify/napalm,spotify/napalm,napalm-automation/napalm