Set directory paths used with dedicated build node

Change-Id: Ie1b6301e5cd788504d792af387c976339ce17f13
diff --git a/config/sample.yml b/config/sample.yml
index bf3d680..4a5adbc 100644
--- a/config/sample.yml
+++ b/config/sample.yml
@@ -14,6 +14,9 @@
   # directories on the head node that the cord dir is copied to, and profile is created in
   cord_dir: '/opt/cord'
   cord_profile_dir: '/opt/cord_profile'
+  credentials_dir: '/opt/credentials'
+  pki_dir: '/opt/pki'
+  ssh_pki_dir: '/opt/ssh_pki'
 
   # Network address information for the head node:
   #