As discussed in nf-core/website#93 and started by @ewels in nf-core/website#87, I moved most of our current documentation into the central webpage https://nf-co.re.

I'm currently keeping in the template:

• README, that links now to the central homepage for most of the documentation (links will work as soon as Move lots of general docs to webpage website#93 is merged)
• Usage, as this is the part that will differ between pipelines all the time.
• Output, as this is also differing most between pipelines and a central location doesn't make sense either.

PR checklist

• This comment contains a description of changes (with reason)
• If you've fixed a bug or added code that should be tested, add tests!
• Documentation in docs is updated
• CHANGELOG.md is updated
• README.md is updated