rust stages for armv6/7-linux-gnueabi{hf} from static.rust-lang.org do not include rust-docs anymore

[stefson]

This is valid for >=rust-1.26.0, the rust-docs folder has been included before that version. For instance with rust-1.25.0 it was just fine. I know that there is a thing called rustup, but there are various reasons to prefere an install from the stage archives via install.sh

There were a few problems with cross compile and rust-docs in the past, this may be related somehow.

Please include rust-docs in the future, if there is a reason not to do that please communicate it. And also please check other archs for the same error, I can only speak for armv6/7! Thanks!

[Mark-Simulacrum]

We no longer build documentation for these platforms; I believe the expectation is that users will use linux (x86_64-unknown-linux-gnu) documentation instead.

cc @alexcrichton