Prolog cookbook: fix several examples.

* The Example 13: 1+1=2 Code-Review was broken, the fix was missing in I131e2008ba
  previous fix. Fix the following error:
    test output invalid result: submit(label(Code-Review,ok(_535EC2E6))). Reason: A label with the status Code-Review: OK must contain a user.

* Example 6: Make change submittable if commit author is "John Doe" was
  probably missing the user(ID)

Change-Id: I4126f01d979b4511faa83d4f779f83599c51c29a
diff --git a/Documentation/prolog-cookbook.txt b/Documentation/prolog-cookbook.txt
index 1c114e2..78497eb 100644
--- a/Documentation/prolog-cookbook.txt
+++ b/Documentation/prolog-cookbook.txt
@@ -544,6 +544,7 @@
     Author = label('Author-is-John-Doe', need(_)).
 
 submit_rule(submit(Author)) :-
+    A = user(1000000),
     gerrit:commit_author(A, 'John Doe', 'john.doe@example.com'),
     Author = label('Author-is-John-Doe', ok(A)).
 ----
@@ -899,7 +900,10 @@
     findall(X, gerrit:commit_label(label(Category,X),R),Z),
     sum_list(Z, Sum),
     Sum >= Min, !,
-    P = [label(Category,ok(R)) | In].
+    gerrit:commit_label(label(Category, V), U),
+    V >= 1,
+    !,
+    P = [label(Category,ok(U)) | In].
 
 add_category_min_score(In, Category,Min,P) :-
     P = [label(Category,need(Min)) | In].