Mention remote name instead of "its developer"

[cassidyjames]

Equally, it might not be entirely right to say the app is "provided solely by its developer". Packages on Flathub are ideally maintained by the developers of the software, but not always.

Originally posted by @ids1024 in #80 (comment)

We currently say apps are provided by their developers, but that's not precise; technically all we know is that an app is provided by the distributor/remote.

See also: elementary/appcenter#1132 (comment)

[Marukesu]

So, I tried to not change soo much from the actual text.

This app is provided by “RemoteName” and has not been reviewed for security, privacy or system integration by elementary.