Merge pull request #702 from ithinuel/improve-spi-peripheral-document…

…ation

Improve `Spi::new` documentation

rp2040-hal/src/spi.rs

@@ -254,6 +254,11 @@ impl<S: State, D: SpiDevice, P: ValidSpiPinout<D>, const DS: u8> Spi<S, D, P, DS
 impl<D: SpiDevice, P: ValidSpiPinout<D>, const DS: u8> Spi<Disabled, D, P, DS> {
     /// Create new not initialized Spi bus. Initialize it with [`.init`][Self::init]
     /// or [`.init_slave`][Self::init_slave].
+    ///
+    /// Valid pin sets are in the form of `(Tx, Sck)` or `(Tx, Rx, Sck)`
+    ///
+    /// If you pins are dynamically identified (`Pin<DynPinId, _, _>`) they will first need to pass
+    /// validation using their corresponding [`ValidatedPinXX`](ValidatedPinTx).
     pub fn new(device: D, pins: P) -> Spi<Disabled, D, P, DS> {
         Spi {
             device,