Ignore yarn.lock file (#2959)

ezhlobo · ForbesLindesay · commit 3750dfef23b4 · 2018-02-13T17:49:52.000Z
diff --git a/.gitignore b/.gitignore
@@ -11,3 +11,4 @@ npm-debug.log
 .release.json
 lerna-debug.log
 package-lock.json
+yarn.lock
