Change "secrete" to "secret"

Apparently this is intentional as a joke on devstack leaking
passwords, but the dual meaning of the word confuses people.  Let's
change it before we get yet another review fixing it.

Change-Id: I3bee03612f6ea197362aab04a37f81043f77f235
diff --git a/doc/source/configuration.rst b/doc/source/configuration.rst
index e985bdc..0493f8f 100644
--- a/doc/source/configuration.rst
+++ b/doc/source/configuration.rst
@@ -104,7 +104,7 @@
 ::
 
     [[local|localrc]]
-    ADMIN_PASSWORD=secrete
+    ADMIN_PASSWORD=secret
     DATABASE_PASSWORD=$ADMIN_PASSWORD
     RABBIT_PASSWORD=$ADMIN_PASSWORD
     SERVICE_PASSWORD=$ADMIN_PASSWORD