TBR: ref: Add '/.jiri' to .gitignore in all repos.

Change-Id: Ida3b446095be214480fafd3f1260adbedb9a4fd7
MultiPart: 10/28
PresubmitTest: none
diff --git a/.gitignore b/.gitignore
index ebef272..cd59ac6 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,2 +1,4 @@
+/.jiri
+#TODO(nlacasse): Get rid of .v23 below once v23->jiri transition is complete.
 /.v23
 **/.DS_Store