fix another duplicate HTML IDs in faq.html

Ran `make gen_top_html` to perform the above.

faq.html

@@ -2315,7 +2315,8 @@ is a valid entry ID.</p>
 <p>See <a href="#fix_author">FAQ 5.5</a> for information about how to update
 and/or correct IOCCC author information.</p>
 <div id="faq6_7">
-<div id="entry_id">
+<!-- we cannot use id="entry_id" because of a header in FAQ 6.6 -->
+<div id="entry_id_faq">
 <h3 id="faq-6.7-what-is-a-entry_id">FAQ 6.7: What is a entry_id?</h3>
 </div>
 </div>

faq.md

@@ -3259,7 +3259,8 @@ and/or correct IOCCC author information.
 
 
 <div id="faq6_7">
-<div id="entry_id">
+<!-- we cannot use id="entry_id" because of a header in FAQ 6.6 -->
+<div id="entry_id_faq">
 ### FAQ 6.7: What is a entry_id?
 </div>
 </div>