Downloading artifacts from Rust's CI

[nikomatsakis]

There is an awesome utility by @kennytm with the short and pithy name rustup-toolchain-install-master. What this does is to download the artifacts produced by Rust's CI for a specific SHA1 -- this basically corresponds to the successful landing of some PR -- and then sets them up for your local use. (@kennytm -- does this include @bors try artifacts as well?) This is helpful when you want to examine the resulting build of a PR without doing the build yourself.

We should mention this tool somewhere, it's super useful!

[nikomatsakis]

(This feels on topic, but maybe it'd be better for forge?)

[kennytm]

does this include @bors try artifacts as well?

Yes, because try builds and normal builds are deployed into the same folder on S3. (But for sure try builds are only available for Linux x86_64.)

[mark-i-m]

I think we might want to make a separate chapter on infrastructure and put bors, crater, CI, and this into that new chapter.

[dwijnand]

I think something short and sweet like #216 would already be very useful.