Merge branch 'content_revision' into 'master'

...ith-it4innovations/accessing-the-clusters/introduction.md

...sing-the-clusters/shell-access-and-data-transfer/putty.md

docs.it4i/salomon/outgoing-connections.md

docs.it4i/salomon/shell-and-data-access.md

docs.it4i/salomon/vpn-access.md

mkdocs.yml