Fix small typos

[KonstHardy]

Hello,
I've found some minor typos in the documentation, solved with this PR.

Fix typo:
overriden -> overridden
typechecks -> type checks
hard coded -> hardcoded

[sizebot]

Comparing: 13455d2...d9dd984

Critical size changes

Includes critical production bundles, as well as any change greater than 2%:

Name	+/-	Base	Current	+/- gzip	Base gzip	Current gzip
oss-stable/react-dom/cjs/react-dom.production.min.js	=	129.55 kB	129.55 kB	=	41.43 kB	41.43 kB
oss-experimental/react-dom/cjs/react-dom.production.min.js	=	134.52 kB	134.52 kB	=	42.89 kB	42.90 kB
facebook-www/ReactDOM-prod.classic.js	=	423.36 kB	423.36 kB	=	78.05 kB	78.05 kB
facebook-www/ReactDOM-prod.modern.js	=	411.92 kB	411.92 kB	=	76.30 kB	76.30 kB
facebook-www/ReactDOMForked-prod.classic.js	=	423.36 kB	423.36 kB	=	78.06 kB	78.06 kB

Significant size changes

Includes any change greater than 0.2%:

(No significant changes)

Generated by 🚫 dangerJS against d9dd984

[bvaughn]

Sure :)