Remove reference to Ring (website debian and debian based download instructions)

Thank you @atraczyk for resolving https://git.jami.net/savoirfairelinux/ring-client-windows/issues/457.

At https://dl.jami.net/ ring is shown in the name of some folders/directories and a file.

Could ring please be removed from the name of the folders/directories and the file?

• ring-internal → internal
• ring-manual-internal → manual-internal
• ring-manual-nightly → manual-nightly
• ring-manual → manual
• ring-nightly → nightly
• ring-release → release
• ring.pub.key → jami.pub.key (or pub.key)
• ring → jami (or app)

What do you think?

Thank you