Update documentation for FullDuplex to try_ methods

Author: david-sawatzke

src/spi.rs

@@ -8,12 +8,12 @@ use nb;
 ///
 /// - It's the task of the user of this interface to manage the slave select lines
 ///
-/// - Due to how full duplex SPI works each `read` call must be preceded by a `send` call.
+/// - Due to how full duplex SPI works each `try_read` call must be preceded by a `try_send` call.
 ///
-/// - `read` calls only return the data received with the last `send` call.
+/// - `try_read` calls only return the data received with the last `send` call.
 /// Previously received data is discarded
 ///
-/// - Data is only guaranteed to be clocked out when the `read` call succeeds.
+/// - Data is only guaranteed to be clocked out when the `try_read` call succeeds.
 /// The slave select line shouldn't be released before that.
 ///
 /// - Some SPIs can work with 8-bit *and* 16-bit words. You can overload this trait with different