Add template for github issues

Reviewed By: KaimingHe

Differential Revision: D6842986

fbshipit-source-id: c8370e2f831239b5489dc723738c6bdf5708a40d

.github/issue_template.md

+## PLEASE FOLLOW THESE INSTRUCTIONS BEFORE POSTING
+1. Please thoroughly read README.md, INSTALL.md, GETTING_STARTED.md, and FAQ.md
+2. Please search existing *open and closed* issues in case your issue has already been reported
+3. Please try to debug the issue in case you can solve it on your own before posting
+
+## After following steps 1-3 above and agreeing to provide the detailed information requested below, you may continue with posting your issue
+(**Delete this line and the text above it.**)
+
+### Expected results
+
+What did you expect to see?
+
+### Actual results
+
+What did you observe instead?
+
+### Detailed steps to reproduce
+
+E.g.:
+
+```
+The command that you ran
+```
+
+### System information
+
+* Operating system: ?
+* Compiler version: ?
+* CUDA version: ?
+* cuDNN version: ?
+* NVIDIA driver version: ?
+* GPU models (for all devices if they are not all the same): ?
+* `PYTHONPATH` environment variable: ?
+* `python --version` output: ?
+* Anything else that seems relevant: ?