Docs: rename form checks page to "Checks / radios" (#31090)

Docs: rename form checks page to "Checks / radios" (#31090)

* Docs: rename form checks page to "Checks / radios"

it's not immediately obvious that "checks" includes information about both checkboxes and radio buttons. while "checks / radios" is also still not perfect (as honestly even I didn't quite grok that "checks" meant checkboxes), it should make it slightly more obvious nonetheless