Modify rule S2808: add diff view and documentation link

rules/S2808/cfamily/rule.adoc

@@ -1,11 +1,11 @@
 == Why is this an issue?
 
-The ``++delete++`` operator expects a pointer argument. Passing it an object may compile and seem to run (with an implicit cast to pointer type) but it can result in unexpected behavior at runtime.
+The ``++delete++`` operator expects a pointer argument. Passing an object to it may compile and seem to run (with an implicit cast to pointer type), but it can result in unexpected behavior at runtime.
 
 
 === Noncompliant code example
 
-[source,cpp]
+[source,cpp,diff-id=1,diff-type=noncompliant]
 ----
 class CString {
 public:
@@ -23,15 +23,24 @@ void fun() {
 
 === Compliant solution
 
-[source,cpp]
+[source,cpp,diff-id=1,diff-type=compliant]
 ----
+class CString {
+public:
+  operator const char*();
+  // ...
+};
+
 void fun() {
   CString *pstr = new CString;
   // ...
   delete pstr;
 }
 ----
 
+== Resources
+
+* {cpp} reference - https://en.cppreference.com/w/cpp/memory/new/operator_delete[operator delete]
 
 ifdef::env-github,rspecator-view[]