TBR: media-sharing: Add '/.jiri' to .gitignore in all repos.

Change-Id: Ie77dbba346c7e42122f2565103da8c135a33ae7a
MultiPart: 20/28
PresubmitTest: none
diff --git a/.gitignore b/.gitignore
index a44eefe..722f46d 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,3 +1,5 @@
+/.jiri
+#TODO(nlacasse): Get rid of .v23 below once v23->jiri transition is complete.
 /.v23
 /android/.idea/
 /android/*.iml