Add yamllint config to template

[JoseEspinosa]

Adds a .yamllint.yml config to avoid line too long and missing document start "---" errors.

Closes #1407

PR checklist

• This comment contains a description of changes (with reason)
• CHANGELOG.md is updated

[mashehu]

For completeness sake, should we also have yamllint for the tools repo itself?

[maxulysse]

For completeness sake, should we also have yamllint for the tools repo itself?

I'd say even for all repos with yml files

[mashehu]

Which ones are left? Modules has it. nfco.re not yet.

[maxulysse]

Which ones are left? Modules has it. nfco.re not yet.

technically every repo with some GHA has some yml, so configs could need that as well

[maxulysse]

While we're at it, we should probably add it to our extension pack on vs code: https://github.com/nf-core/vscode-extensionpack

[JoseEspinosa]

Will add it to tools in this same PR