Add links for issues

Author: astapleton

README.md

@@ -39,11 +39,11 @@ of support for peripherals is shown in the table below.
 | ICache     | ✅ | - | |
 | I2C        | ✅ | - | Controller operation is done; Target is 🚧 |
 | CAN        | 🚧 | - | |
-| Rng        | 🚧 | #34| |
-| SPI        | 🚧 | #36 | |
+| Rng        | 🚧 | [#34](https://github.com/stm32-rs/stm32h5xx-hal/issues/34)| |
+| SPI        | 🚧 | [#36](https://github.com/stm32-rs/stm32h5xx-hal/issues/36) | |
 | UART       | 🚧 | - | |
 | DMA        | 🚧 | - | |
-| ADC        | ❌ | #35 | |
+| ADC        | ❌ | [#35](https://github.com/stm32-rs/stm32h5xx-hal/issues/35) | |
 | Timers     | ❌ | - | |
 | PWM        | ❌ | - | |
 | Rtc        | ❌ | - | |