Improved docs with custom logo and favicon

lib/runtime-abi/src/lib.rs

@@ -1,4 +1,8 @@
 #![deny(dead_code, unused_imports, unused_variables, unused_unsafe, unreachable_patterns)]
+
+#![doc(html_favicon_url = "https://wasmer.io/static/icons/favicon.ico")]
+#![doc(html_logo_url = "https://avatars3.githubusercontent.com/u/44205449?s=200&v=4")]
+
 #[cfg(not(target_os = "windows"))]
 #[macro_use]
 extern crate failure;