[readme] fix formating

Yamakaky · Yamakaky · commit 4dd7f0292d0a · 2016-11-18T23:06:53.000-05:00
diff --git a/README.md b/README.md
@@ -13,6 +13,7 @@ provides a few unique features:
 * Errors can create and propagate backtraces.
 
 [Documentation (crates.io)](https://docs.rs/error-chain).
+
 [Documentation (master)](https://brson.github.io/error-chain).
 
 ## Quick start
