Split out 'nf-core run' from Hello nf-core

[vdauwera]

Part 1 can stay as is. Consider adding a Part 2 covering inputs (samplesheets) and parameterization.

Any other topics of interest for run-only purposes?

Could add an exercise of picking a pipeline for a given domain (maybe out of a specific set) and running, to illustrated usage in that domain. This would serve the purpose of what Ken did for imaging?

[vdauwera]

This needs a bit more scoping out so will deal with it as a separate project.

[vdauwera]

Decided against doing this; just making Part 1 more fit to purpose / moving some content over to Part 2. Will communicate clearly that Part 1 can be used for user-only purposes.

See #899