fix "maintiner" typo
Merge pull request #3607 from aspiers/maintiner-typo

fix "maintiner" typo
core: Allow insecure RubyGems for plugins [GH-3610]
website/docs: don't need a static IP for NFS [GH-3608]
providers/virtualbox: remove old print
Update net-ssh dep [GH-3605]
communicators/ssh: detect if config.ssh.shell is non-functional [GH-3040]
Update completion.sh
website/docs: update box format [GH-3613]
website/docs: virtualbox [GH-3609]
split off virtualbox networking into separate page

v2/networking/index.html.md encourages the reader to seek
provider-specific information under the documentation for the provider,
so for consistency, any virtualbox-specific networking info should be
placed there, not in the general networking section.