Add additional meta data to improve crate experience

* Add readme setting, so README.md is shown on https://crates.io/

Author: Nicoretti

Cargo.toml

@@ -6,6 +6,7 @@ documentation = "https://docs.rs/cortex-m"
 keywords = ["arm", "cortex-m", "register", "peripheral"]
 license = "MIT OR Apache-2.0"
 name = "cortex-m"
+readme = "README.md"
 repository = "https://github.com/japaric/cortex-m"
 version = "0.5.7"
 
@@ -17,4 +18,4 @@ volatile-register = "0.2.0"
 [features]
 cm7-r0p1 = []
 const-fn = ["bare-metal/const-fn"]
-inline-asm = []
+inline-asm = []