backend documents mirrors examples crates

sections was added was added to the examples crate to show the
usage of new api (6a8bb87), but the examples crate is not
published on `crates.io` and `docs.rs`, this commit updates
brings the same example code to the documents of the backend
crates `gpu-alloc-ash` and `gpu-alloc-erupt`.

ash/src/lib.rs

@@ -74,6 +74,30 @@
 //!
 //!     unsafe { allocator.dealloc(AshMemoryDevice::wrap(&device), block) }
 //!
+//!     // the `ash::Device` also implements `AsRef<AshMemoryDevice>`
+//!     // you can pass a reference of `ash::Device` directly as argument
+//!     let mut block = unsafe {
+//!         allocator.alloc(
+//!             &device,
+//!             Request {
+//!                 size: 10,
+//!                 align_mask: 1,
+//!                 usage: UsageFlags::HOST_ACCESS,
+//!                 memory_types: !0,
+//!             },
+//!         )
+//!     }?;
+//!
+//!     unsafe {
+//!         block.write_bytes(
+//!             &device,
+//!             0,
+//!             &[0, 1, 2, 3, 4, 5, 6, 7, 8, 9],
+//!         )
+//!     }?;
+//!
+//!     unsafe { allocator.dealloc(&device, block) }
+//!
 //!     Ok(())
 //! }
 //! ```

erupt/src/lib.rs

@@ -78,6 +78,30 @@
 //!
 //!     unsafe { allocator.dealloc(EruptMemoryDevice::wrap(&device), block) }
 //!
+//!     // the `erupt::DeviceLoader` also implements `AsRef<EruptMemoryDevice>`
+//!     // you can pass a reference of `erupt::DeviceLoader` directly as argument
+//!     let mut block = unsafe {
+//!         allocator.alloc(
+//!             &device,
+//!             Request {
+//!                 size: 10,
+//!                 align_mask: 1,
+//!                 usage: UsageFlags::HOST_ACCESS,
+//!                 memory_types: !0,
+//!             },
+//!         )
+//!     }?;
+//!
+//!     unsafe {
+//!         block.write_bytes(
+//!             &device,
+//!             0,
+//!             &[0, 1, 2, 3, 4, 5, 6, 7, 8, 9],
+//!         )
+//!     }?;
+//!
+//!     unsafe { allocator.dealloc(&device, block) }
+//!
 //!     Ok(())
 //! }
 //! ```