Change data sharing options

I propose to change the data sharing section of the README.md to

  - Data sharing options depend on the data size:
      - For data < ~100 MB, use the folder structure of the repo and place your data under `data/input`.
      - For data < ~5 GB, use [EMBL ownCloud](https://oc.embl.de/index.php/login)
      - Otherwise, use EMBL S3-compatible object store (ask ITS).
		   
- Data will need to be deposited on public archives (such as [Bioimage archive](https://www.ebi.ac.uk/bioimage-archive/)) for publication purposes.