Fix wasm32v1-none compilation errors

- arrayvec.rs: Use concrete return types ([T], slice::Iter, slice::IterMut)
  instead of Self::Target/Self::IntoIter to avoid E0223 ambiguity
  introduced by the Receiver trait in Rust 1.87+
- char.rs: Explicitly import Result/Ok/Err from core for target_os=none
  where the standard prelude is not auto-injected

README.md

@@ -0,0 +1,27 @@
+
+arrayvec
+========
+[![Crates.io: arrayvec](https://img.shields.io/crates/v/arrayvec.svg)](https://crates.io/crates/arrayvec)
+[![Documentation](https://docs.rs/arrayvec/badge.svg)](https://docs.rs/arrayvec)
+[![Build Status](https://github.com/bluss/arrayvec/workflows/Continuous%20integration/badge.svg?branch=master)](https://github.com/bluss/arrayvec/actions)
+
+
+
+
+[![License: Apache](https://img.shields.io/badge/License-Apache%202.0-red.svg)](LICENSE-APACHE)
+OR
+[![License: MIT](https://img.shields.io/badge/license-MIT-blue.svg)](LICENSE)
+
+A vector with fixed capacity.
+
+Please read the [`API documentation here`](https://docs.rs/arrayvec)
+
+# License
+
+Dual-licensed to be compatible with the Rust project.
+
+Licensed under the Apache License, Version 2.0
+http://www.apache.org/licenses/LICENSE-2.0 or the MIT license
+http://opensource.org/licenses/MIT, at your
+option. This file may not be copied, modified, or distributed
+except according to those terms.