Add issues template

1. Should move templates to .github/ 
2. Add issues template with the following:

```
## Description

...

## Environment

- JsonApiDotNetCore Version: 
- Non-transitive/overridden package versions:
   - AspNetCore:
   - EntityFrameworkCore:
   - ...
```

REF: https://blog.github.com/2016-02-17-issue-and-pull-request-templates/