Auto merge of #7549 - ehuss:minimal-versions-note, r=alexcrichton
Auto merge of #7549 - ehuss:minimal-versions-note, r=alexcrichton

Add a note to discourage the use of -Zminimal-versions.

We've discussed this a few times, that the current implementation isn't working out, so let's be more transparent about it.

tshepang/cargo,rustyhorde/cargo,tsurai/cargo,nipunn1313/cargo,rust-lang/cargo,eminence/cargo,rust-lang/cargo,vojtechkral/cargo,eminence/cargo,vojtechkral/cargo,tsurai/cargo,nipunn1313/cargo,tshepang/cargo,rustyhorde/cargo,nipunn1313/cargo,rust-lang/cargo,tsurai/cargo,rust-lang/cargo,tsurai/cargo,vojtechkral/cargo,eminence/cargo,eminence/cargo,rustyhorde/cargo,tshepang/cargo,vojtechkral/cargo,nipunn1313/cargo,rustyhorde/cargo,tshepang/cargo,tsurai/cargo