Conditionally include sdcard module

Co-authored-by: Vadim Kaushan <[email protected]>

Author: gschwaer

src/lib.rs

@@ -10,4 +10,6 @@ pub use gd32vf103xx_hal as hal;
 pub mod lcd;
 pub mod led;
 pub mod stdout;
+#[cfg(feature = "sdcard")]
+#[cfg_attr(docsrs, doc(cfg(feature = "sdcard")))]
 pub mod sdcard;