Migrate from `doc_auto_cfg` to `doc_cfg` (#740) #1325

Job	Run time
set-msrv / set-msrv	4s
minimal-versions / minimal-versions	40s
build (1.85.0, thumbv7em-none-eabi)	25s
build (stable, thumbv7em-none-eabi)	24s
build (stable, wasm32-unknown-unknown)	27s
build (1.85.0, wasm32-unknown-unknown)	26s
test (1.85.0)	30s
test (stable)	30s
	3m 26s

Provide feedback