Add github issue templates

.github/ISSUE_TEMPLATE/bug_report.md

+---
+name: Bug report
+about: Create a report to help us improve
+
+---
+
+**What version of protobuf and what language are you using?**
+Version: master/v3.6.0/v3.5.0 etc.
+Language: C++/Java/Python/C#/Ruby/PHP/Objective-C/Javascript
+
+**What operating system (Linux, Windows, ...) and version?**
+
+**What runtime / compiler are you using (e.g., python version or gcc version)**
+
+**What did you do?**
+Steps to reproduce the behavior:
+1. Go to '...'
+2. Click on '....'
+3. Scroll down to '....'
+4. See error
+
+**What did you expect to see**
+
+**What did you see instead?**
+
+Make sure you include information that can help us debug (full error message, exception listing, stack trace, logs).
+
+**Anything else we should know about your project / environment**

.github/ISSUE_TEMPLATE/feature_request.md

+---
+name: Feature request
+about: Suggest an idea for this project
+
+---
+
+**What language does this apply to?**
+If it's a proto syntax change, is it for proto2 or proto3?
+If it's about generated code change, what programming language?
+
+**Describe the problem you are trying to solve.**
+
+**Describe the solution you'd like**
+
+**Describe alternatives you've considered**
+
+**Additional context**
+Add any other context or screenshots about the feature request here.

.github/ISSUE_TEMPLATE/question.md

+---
+name: Question
+about: Questions and troubleshooting
+
+---
+
+