Add FAQ about mismatch of source/author remarks

This felt important because numerous times I have had to put in a
README.md file and/or the thanks file that state that the authors' or
author's remarks no longer apply and what should be done about it. These
should be located and either be removed or be synchronised (or even
refer to the FAQ?).

faq.md

@@ -223,6 +223,13 @@ make DIFF=colordiff diff_alt_prog # for alt to prog diff
 Obviously if you want to view the alt code or the orig code you can just open
 the files as described above.
 
+## Q: Sometimes the author's or authors' remarks do not match the source! Why and what can I do about it?
+
+This is very likely to happen when an entry was fixed for modern systems. When
+you look at the remarks of the author you should look at the `prog.orig.c` or
+the `winner.orig.c` file. You might also find value in the above `diff` make
+rules.
+
 
 ## Q: I cannot get entry XYZZY from year 19xx to compile!