Documentation update

[kbestak]

I'll write issues found in the Documentation here for reference when they are fixed:

• CITATIONS.md
  • weird indentations for ilastik and mesmer https://github.com/nf-core/molkart/blob/dev/CITATIONS.md#pipeline-tools
• README.md
  • workflow too small
  • update workflow with newer version
  • "image preprocessing" leftover? - add other headers also
  • output description missing
  • samplesheet.csv example has a space
• USAGE.md
  • separartor
  • make sure example samplesheet exists
  • make sure params work
  • make it clearer conda is not supported
  • explain that running mixed samples possible, but that segmentation is applied as if comparable samples are used, e.g ilastik cannot handle different images as the project file defines if it is 1 or 2 channel.
• OUTPUT.md
  • rewrite so that it reads better
  • MolkartQC - fix headers
  • combined qc metric file?

Can we remove run with conda tag on first page?

[kbestak]

Addressed in: #33