Docs: added note about setState() side-effects
Docs: added note about setState() side-effects

(cherry picked from commit 1219663e9a63862d39538c75f4a60993d5d4d48a)

mtsyganov/react,mtsyganov/react,odysseyscience/React-IE-Alt,mtsyganov/react,odysseyscience/React-IE-Alt,odysseyscience/React-IE-Alt,odysseyscience/React-IE-Alt,odysseyscience/React-IE-Alt,mtsyganov/react