Add pki dir to .gitignore

Change-Id: I2ed9258281ce84fea67f63ea36281d2dbd75426f
diff --git a/.gitignore b/.gitignore
index 045bbce..893e354 100644
--- a/.gitignore
+++ b/.gitignore
@@ -45,3 +45,6 @@
 
 # Backup files
 *.bak
+
+# PKI dir
+pki/