Clean up formatting from #31

Author: dtolnay

README.md

@@ -218,7 +218,7 @@ Attribute macro to skip serializing all fields of Option type<br>
 <a href="https://github.com/serde-rs/serde/issues/947">[Origin]</a>
 —
 <a href="https://github.com/dtolnay/request-for-implementation/issues/18">[Design]</a>
-- 
+—
 <a href="https://docs.rs/serde_with_macros/1.0/serde_with_macros/attr.skip_serializing_none.html">[Outcome]</a>
 </td></tr></table>
 </blockquote>