SUPPORT file support in repository
### Description
To point contributors to where they can find support, a `SUPPORT` file can be useful.
This was a good idea by GitHub: https://github.com/blog/2400-support-file-support
### Proposal
Support this filetype by quick linking to it from the project home page and showing it when creating a new issue when it's present in the `.gitlab` directory of the repository.
### Links / references
### Documentation blurb
#### Overview
What is it?
Why should someone use this feature?
What is the underlying (business) problem?
How do you use this feature?
#### Use cases
Who is this for? Provide one or more use cases.
### Feature checklist
Make sure these are completed before closing the issue,
with a link to the relevant commit.
- [ ] [Feature assurance](https://about.gitlab.com/handbook/product/#feature-assurance)
- [ ] Documentation
- [ ] Added to [features.yml](https://gitlab.com/gitlab-com/www-gitlab-com/blob/master/data/features.yml)
issue