Create documentation for file management

[SebastianPrehn]

Create a page outlining the different ways of transferring files, and make sure that there is adequate documentation for each method.

We need documentation for the following:

• WebDAVS
• SFTP
  • Filezilla
  • rclone
• rsync (potentially)

[SebastianPrehn]

WebDAVS should be covered as of 642ed20

[SebastianPrehn]

Will also need information related to sharelinks for SFTP, as they provide quite a lot of features. Information about it can be found in the user guide