Add documentation to TextInput's Flow types (#26054)

Summary:
The documentation from the Flow types' respective proptypes have been copied over to `TextInput`.

## Changelog

[Internal] [Changed] - Added documentation to TextInput's Flow types
Pull Request resolved: #26054

Test Plan: `yarn flow-check-ios` and `yarn flow-check-android` both pass.

Differential Revision: D16801435

Pulled By: TheSavior

fbshipit-source-id: 7f3d75ba149259d5bbf719375320e2e325188826