Add errata links

Author: chemicstry

src/sdio.rs

@@ -247,7 +247,9 @@ impl<P: SdioPeripheral> Sdio<P> {
                 .rising()
                 // Do not use hardware flow control.
                 // Using it causes clock glitches and CRC errors.
-                // See chip errata SDIO section.
+                // See chip errata SDIO section:
+                // - F42x/F43x: https://www.st.com/resource/en/errata_sheet/es0206-stm32f427437-and-stm32f429439-line-limitations-stmicroelectronics.pdf
+                // - F40x/F41x: https://www.st.com/resource/en/errata_sheet/es0182-stm32f405407xx-and-stm32f415417xx-device-limitations-stmicroelectronics.pdf
                 .hwfc_en()
                 .disabled()
         });