Add issue templates

[9oelM]

Rationale

Currently, Typedoc does not have issue templates, so I have raised an issue on that (#928)
Many people are graciously giving contributions, but sometimes it's hard to understand their intentions or problems. Therefore it seems it's a better approach to make an issue template.

Templates

• Typedoc's issues can largely be divided into two: bug reports (i.e. Interface is displayed twice when both child and base classes implement it. #893, No reflection on object literals #901, @category not working for functions within modules #904, ...) and suggestions (i.e. Refactor to use array include #898, Provide an option to link standard classes to MDN #895, Feature Request: Instead of showing links to types/aliases/interfaces, show their information instead #902, ...). That's the reason I made separate templates for each.
• I believe these templates are fully in line with what @Gerrit0 is saying in CONTRIBUTING.md.

Goal

I tried to lead contributors to the right direction but did not want to annoy them with a bunch of lines of comments. Plus, as @aciccarello said, I wanted to keep it as simple as possible for the risk of submissions of issues with almost no information hidden under an already-well-written template of length.

[aciccarello]

Thanks for putting this together! Could we make some improvements to the working?

[aciccarello]

Thanks for updating. A few more minor changes before we enable this.

[aciccarello]

Thanks for putting this together!