Github: add different issue templates

.github/ISSUE_TEMPLATE → .github/ISSUE_TEMPLATE/bugreport.md

+---
+name: Bug Report
+about: Use this template for reporting Bugs
+---
+
 !!!IMPORTANT!!!: To facilitate faster and easier response to your issue please provide in addition to the description of the issue also the following information
 
- - OS version: e.g. SLC6
- - Compiler version: e.g GCC 6.2
- - DD4hep version: tag or commit ID, or GitHub branch
- - Reproduced by: exact steps to reproduce the problem: checkout, setup environment (Geant, ROOT versions, iLCSoft release), cmake, build, run...
+ - OS version: e.g. centos7
+ - Compiler version: e.g GCC 8.0
+ - Package version: tag or commit ID, or GitHub branch
+ - Reproduced by: exact steps to reproduce the problem: checkout, setup environment (Geant4/ROOT version, LCG/iLCSoft/Key4hep release), cmake, build, run...
  - Input: link to input files if applicable
  - Output: full build and run log output
  - Goal: A short description of what you are trying to achieve

.github/ISSUE_TEMPLATE/feature.md

+---
+name: New Feature
+about: Use this template for proposing new features
+labels: enhancement
+---
+

.github/ISSUE_TEMPLATE/question.md

+---
+name: Question
+about: Use this template for asking questions about the functionality of DD4hep
+labels: question
+---