Remove duplicate 'note:'

Author: jyn514

README.md

@@ -7,8 +7,8 @@ standard library, and documentation.
 
 [Rust]: https://www.rust-lang.org
 
-**Note: this README is for _users_ rather than _contributors_.**
-**Note: If you wish to _contribute_ to the compiler, you should read the
+**Note: this README is for _users_ rather than _contributors_.
+If you wish to _contribute_ to the compiler, you should read the
 [Getting Started][gettingstarted] of the rustc-dev-guide instead of this
 section.**