[P.6] copyedit: Move a comment for consistency, change "a" to "the", and fix a typo: "f" to "f2" (#2288)

* [P.6] trivial: s/f/f2/ (#2288)

A comment in a code example was intended to refer to a function named "f2",
but the comment uses the name "f" instead, presumably because the code was
copied from the previous example; this commit fixes the typo.

* [P.6] trivial: Move a code comment (//...) to the line above the code (#2288)

This matches the way the previous, related code example is written,
a fact you can observe more readily by reviewing the patch of this
commit with larger context:

    git diff -U19

Specifically, the previous example looks like this:

    // bad: the number of elements is not passed to f()
    f(new int[n]);

* [P.6] trivial: s/a/the/ (#2288)

While "a wrong number can be passed" makes sense (and there are perhaps
good philosophical reasons to prefer it), I believe that the more natural
way to say it in common English is "the wrong number can be passed"; thus,
this commit changes "a" to "the" in the comment of a code example.

---------

Co-authored-by: Herb Sutter <herb.sutter@gmail.com>

Author: mfwitten

CppCoreGuidelines.md

@@ -767,7 +767,8 @@ We can of course pass the number of elements along with the pointer:
 
     void g2(int n)
     {
-        f2(new int[n], m);  // bad: a wrong number of elements can be passed to f()
+        // bad: the wrong number of elements can be passed to f2()
+        f2(new int[n], n);
     }
 
 Passing the number of elements as an argument is better (and far more common) than just passing the pointer and relying on some (unstated) convention for knowing or discovering the number of elements. However (as shown), a simple typo can introduce a serious error. The connection between the two arguments of `f2()` is conventional, rather than explicit.