Add hash to rustdoc example #3439

Job	Run time
format	24s
bare-metal (src/bare-metal/alloc-example, aarch64-unknown-none)	26s
find-languages	4s
bare-metal (src/bare-metal/aps/examples, aarch64-unknown-none)	34s
bare-metal (src/bare-metal/microcontrollers/examples, thumbv7em-none-eabihf)	1m 3s
cargo (ubuntu-latest)	28s
bare-metal (src/exercises/bare-metal/compass, thumbv7em-none-eabihf)	1m 15s
cargo (macos-latest)	40s
bare-metal (src/exercises/bare-metal/rtc, aarch64-unknown-none)	30s
build (bn)	3m 1s
build (da)	2m 22s
build (de)	3m 2s
build (el)	2m 16s
build (en)	2m 50s
build (es)	2m 56s
build (fa)	2m 28s
build (fr)	3m 10s
build (id)	1m 45s
build (it)	1m 47s
build (ja)	2m 53s
build (ko)	2m 8s
build (pl)	1m 51s
build (pt-BR)	1m 40s
build (ru)	3m 0s
build (tr)	2m 27s
build (uk)	2m 13s
build (zh-CN)	3m 9s
build (zh-TW)	2m 10s
	52m 32s

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