example(sdio): example to use sdmmc host to do SDIO communication with SDIO slave

examples/peripherals/sdio/slave/main/Kconfig.projbuild

@@ -0,0 +1,16 @@
+menu "Example Configuration"
+
+config SDIO_DAT2_DISABLED
+    bool "Disable the DAT2 in SDIO slave"
+    default y
+    help
+        SDIO slave DAT pin is unfortunately the same pin as MTDI, which
+        controls the flash power voltage. For 3.3v flash devkits / modules /
+        kits, it conflicts with the DAT2 pullups required by the
+        specification.
+        
+        This disables the peripheral input from the DAT2 so that we can work
+        in 1-bit mode when DAT2 is floating (pulled down). 4-bit mode is
+        therefore unavailable.
+
+endmenu