Merge pull request #71 from mpuncel/mpuncel/fix-readme

fix bug in example in README

README.md

diff --git a/README.md b/README.md
index 46dd102..01769c7 100644
--- a/README.md
+++ b/README.md
@@ -126,7 +126,7 @@
   // exported logger. See Godoc.
   log.Out = os.Stderr
 
-  log.WithFields(log.Fields{
+  log.WithFields(logrus.Fields{
     "animal": "walrus",
     "size":   10,
   }).Info("A group of walrus emerges from the ocean")