Adds documentation for bitflagsv2

Author: manushT

defmt/src/lib.rs

@@ -361,6 +361,33 @@ pub use defmt_macros::timestamp;
 ///         const ABC = Self::A.bits | Self::B.bits | Self::C.bits;
 ///     }
 /// }
+///
+/// defmt::info!("Flags::ABC: {}", Flags::ABC);
+/// defmt::info!("Flags::empty(): {}", Flags::empty());
+/// ```
+pub use defmt_macros::bitflags;
+
+/// Users of the defmt crate can enable the bitflagsv2 feature by adding defmt = { features = ["bitflagsv2"] } 
+/// to their Cargo.toml. Bitflags version 2 introduces significant improvements over version 1, including a safer 
+/// API with the replacement of the unsafe from_bits_unchecked method by the safe from_bits_retain method 
+/// and enhanced serialization support via an optional serde feature.
+///
+/// This macro is a wrapper around the [`bitflags!`] version 2 crate, and provides an (almost) identical
+/// interface. Refer to [its documentation] for an explanation of the syntax.
+///
+/// [its documentation]: https://docs.rs/bitflags/2/bitflags/
+///
+/// # Limitations
+///
+/// This macro only supports bitflags structs represented as one of Rust's built-in unsigned integer
+/// types (`u8`, `u16`, `u32`, `u64`, or `u128`). Custom types are not supported. This restriction
+/// is necessary to support defmt's efficient encoding.
+///
+/// # Examples
+///
+/// The example from the bitflagsv2 crate works as-is:
+///
+/// ```
 /// #[cfg(feature = "bitflagsv2")]
 /// defmt::bitflagsv2! {
 ///     struct Flags: u32 {
@@ -373,7 +400,6 @@ pub use defmt_macros::timestamp;
 /// defmt::info!("Flags::ABC: {}", Flags::ABC);
 /// defmt::info!("Flags::empty(): {}", Flags::empty());
 /// ```
-pub use defmt_macros::bitflags;
 #[cfg(feature = "bitflagsv2")]
 pub use defmt_macros::bitflagsv2;