Fix peculiar (and ungrammatical) wording in an example program.

Doc/ext/embedding.tex

@@ -145,7 +145,7 @@ it to execute a Python script, such as:
 
 \begin{verbatim}
 def multiply(a,b):
-    print "Thy shall add", a, "times", b
+    print "Will compute", a, "times", b
     c = 0
     for i in range(0, a):
         c = c + b
@@ -156,7 +156,7 @@ then the result should be:
 
 \begin{verbatim}
 $ call multiply 3 2
-Thy shall add 3 times 2
+Will compute 3 times 2
 Result of call: 6
 \end{verbatim} % $