Sync with reactjs.org @ 1f2dbb7a#285

Merged

gcor merged 25 commits intomasterfrom

Apr 2, 2019

Commits on Mar 18, 2019

Add React Rally 2019 (#1840)

BrianMitchL
authored and
alexkrolick
committed

Commits on Mar 19, 2019

Commits on Mar 20, 2019

Update languages for Simplified Chinese completion (#1854)
tesseralis
authored

Commits on Mar 22, 2019

merging all conflicts
reactjs-translation-bot
committed

Commits on Mar 24, 2019

[ru.reactjs.org] fix sync conflicts
gcor
committed

Commits on Mar 30, 2019

Commits on Apr 1, 2019

Commits on Apr 2, 2019