hwdef: add MatekH7A3 readme.md #37489

Job	Run time
build (stm32f7, chibios, 10)	3m 49s
build (stm32h7, chibios, 10)	3m 26s
build (fmuv2-plane, chibios, 10)	1m 53s
build (periph-build, chibios, 10)	3m 38s
build (iofirmware, chibios, 10)	1m 36s
build (CubeOrange-bootloader, chibios, 10)	52s
build (fmuv3-bootloader, chibios, 10)	1m 39s
build (revo-bootloader, chibios, 10)	1m 16s
build (stm32h7-debug, chibios, 10)	2m 22s
build (fmuv3, chibios, 10)	5m 0s
build (revo-mini, chibios, 10)	3m 54s
build (MatekF405-Wing, chibios, 10)	4m 24s
build (CubeOrange-ODID, chibios, 10)	2m 32s
build (CubeRedPrimary-bootloader, chibios, 10)	49s
build (configure-all, chibios, 10)	9m 43s
build (build-options-defaults-test, chibios, 10)	7m 49s
build (signing, chibios, 10)	3m 38s
build (CubeOrange-PPP, chibios, 10)	2m 15s
build (SOHW, chibios, 10)	3m 23s
build (Pixhawk6X-PPPGW, chibios, 10)	1m 14s
	1h 5m 12s

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