Review documentation w.r.t. filesystems and hardware

• Octopus (cf. #609)
  • Nein!
• Remove SSD
• Update numbers based on documented hardware
• Hardware overview page
  • Review
  • Update OS versions
  • Remove information on filesystems; insert links to filesystem pages instead
• Cluster pages
  • Remove filesystem and workspace stuff - what remains?
  • Barnard
  • Power9: Add content; closes #579 (closed)
  • Romeo
  • Julia
  • Alpha Centauri
• Remove documentation on taurusexport
  • Compare export_nodes.md and dataport_nodes~~- [ ]file_systems.mdandworking.md` are almost identical~~ #630