Update readme example to use 0.3 version

malbarbo · malbarbo · commit f37a84bec060 · 2017-05-19T10:39:24.000-03:00
diff --git a/README.md b/README.md
@@ -13,7 +13,7 @@ more stable and programmatic interface.
 
 ```toml
 [dependencies]
-backtrace = "0.2"
+backtrace = "0.3"
 ```
 
 ```rust
