Ignore intellij bazel plugin's data directory

.ijwb is used by bazel intellij plugin to store build status.
Plugin info at: https://github.com/bazelbuild/intellij

Change-Id: Idf4e80f55eb405833068ed8ae6c0cdc4d12d782c
diff --git a/.gitignore b/.gitignore
index d1ddc33..3f8388f 100644
--- a/.gitignore
+++ b/.gitignore
@@ -32,3 +32,4 @@
 /plugins/cookbook-plugin/
 /test_site
 /tools/format
+/.ijwb