[v8.x backport] doc: Backport #19685 and #19949 to v8.x#21590

ChALkeR wants to merge 2 commits intonodejs:v8.x-stagingnodejs/node:v8.x-stagingfrom

ChALkeR:backport-19949-v8xChALkeR/io.js:backport-19949-v8xCopy head branch name to clipboard