C++: more documentation for implict destructor calls

Author: rdmarsh2

cpp/ql/lib/semmle/code/cpp/stmts/Stmt.qll

@@ -62,11 +62,23 @@ class Stmt extends StmtParent, @stmt {
   /**
    * Gets the `n`th compiler-generated destructor call that is performed after this statement, in
    * order of destruction.
+   * 
+   * For instance, in the following code, `getImplicitDestructorCall(0)` for the block will be the
+   * destructor call for `c2`:
+   * ```cpp
+   * {
+   *      MyClass c1;
+   *      MyClass c2;
+   * }
+   * ```
    */
   DestructorCall getImplicitDestructorCall(int n) {
     synthetic_destructor_call(this, max(int i | synthetic_destructor_call(this, i, _)) - n, result)
   }
 
+  /**
+   * Gets a compiler-generated destructor call that is performed after this statement.
+   */
   DestructorCall getAnImplicitDestructorCall() {
     synthetic_destructor_call(this, _, result)
   }