Rollup of 6 pull requests#74387

Closed

Manishearth wants to merge 12 commits intorust-lang:masterfrom

Manishearth:rollup-36nbdbu

Commits on Jul 7, 2020

Update reference to CONTRIBUTING.md
JohnTitor
committed

Commits on Jul 13, 2020

Add and fix BTreeMap comments
ssomers
committed

Commits on Jul 16, 2020

Rollup merge of #73421 - janikrabe:master, r=joshtriplett
Manishearth
authored
Rollup merge of #74037 - JohnTitor:contributing-md, r=Mark-Simulacrum
Manishearth
authored
Rollup merge of #74295 - ssomers:btree_comments, r=Mark-Simulacrum
Manishearth
authored
Rollup merge of #74352 - ehuss:fix-alloc-links, r=Mark-Simulacrum
Manishearth
authored
Rollup merge of #74377 - alexcrichton:test-default, r=Mark-Simulacrum
Manishearth
authored
Rollup merge of #74381 - mbrubeck:docs, r=Mark-Simulacrum
Manishearth
authored