Add an issue template

.github/issue_template.md

+**Help us help you.**
+
+If you are reporting a bug, include:
+
+* a Minimum Working Example without any dependencies (except libc) that shows
+  the issue and ideally reproduces in the Rust playground
+* the target triple - libc supports many targets and many APIs
+* instructions to reproduce, logs (e.g. build logs, links to Travis-CI logs,
+  uploads to github gists, etc.).
+
+If you are requesting a new API, include:
+
+* the target triple
+* link to the documentation of the API showing the type signatures, how to use
+  it, etc.
+
+In general, just please consider that the people who can help you are all very
+busy, they will be helping you in their free time, there are a lot of people in
+need of help so they need to prioritize to which issues they devote their free
+time, etc. So try to give most of the information upfront, be concise, show
+small self-contained examples (nobody has time to create a new cargo project,
+set up dependencies,...), etc. Help us help you.