Add switch-group info to user CLI page
Merge pull request #903 from will-moore/cli_switch_group

Add switch-group info to user CLI page
Add omero fs section to sysadmin docs.
Add omero fs section to user docs and link to sysadmin.
Fixes and typos following review.
Merge pull request #910 from ximenesuk/cli-fs-command

Document CLI command fs