Add example for the usage of ReturnThruPtr

I found it difficult to decipher the correct syntax for using ReturnThruPtr, and looking at github issues and google groups messages suggests others have had the same trouble. I suggest this example to explicate the correct usage.

docs/CMock_Summary.md

@@ -220,6 +220,31 @@ are queued up and copied into the space being pointed at each time the mock is c
 * => `void func_ReturnArrayThruPtr_paramName(val_to_return, len)`
 * => `void func_ReturnMemThruPtr_paramName(val_to_return, size)`
 
+For example, consider the following function:
+
+`BOOL divide(uint numerator, uint denominator, int* result){
+    if (denominator == 0){
+        return FALSE;
+    }
+    *result = numerator/denominator;
+    return TRUE;
+}
+`
+
+We might want to mock this function so that regardless of the inputs, it returns TRUE and a result of 23.
+We could do so like this:
+
+`int result_1 = 23;
+divide_ExpectAnyArgsAndReturn(TRUE);
+divide_ReturnThruPtr_result(&result_1);
+`
+
+If we want to expect a numerator of 5 and a denominator of 2 and return a result of 42:
+`int result_1 = 42;
+divide_ExpectAndReturn(5,2,NULL,TRUE);
+divide_IgnoreArg_result();
+divide_ReturnThruPtr_result(&result_1);
+`
 
 Callback:
 ---------