fix issue 22850 - [Oh No! Page Not Found] Contract Programming

Author: aG0aep6G

articles/cppcontracts.dd

@@ -21,7 +21,8 @@ $(HEADERNAV_TOC)
 $(H2 $(LNAME2 contract-programming-d, Contract Programming in D))
 
         This is more fully documented in the D
-        <a href="contracts.html">Contract Programming</a> document.
+        $(DDLINK spec/contracts, Contract Programming, Contract Programming)
+        document.
         To sum up, Contract Programming in D has the following characteristics:
 
         $(OL