RFE: consider adding man pages

[cuviper]

It is generally expected that CLI programs on unix-like systems should have a man page. Elsewhere in the Rust toolchain, we do have rustc.1, rustdoc.1, cargo.1, and many cargo-*.1 subcommands. It seems reasonable that we could have rustfmt.1 and cargo-fmt.1 as well.

See also rust-lang/rust#98977 for discussion about autogenerating man pages.

[calebcartwright]

This is a fair ask, though not sure when we'll have capacity to get around to it

[davidBar-On]

I am willing to help with this issue, but I am not sure what is the scope of the required solution. Is it only creating a man page file similar to this rustfmt.1t file - created mainly using help2man (its man output text is here)? Are additional activities required, such as automatic install of the file as part of rustfmt install (which I have no idea how to do ...)?

I assume that automatic generation of the man page is not required, as it is also not implemented yet for rustc/rustdoc.