remove XXX from text in faq.md

In several cases where the `faq.md` had **XXX**'s, we replaced the
text with equivalent text for someone to read (such as the **IOCCC
registration procedure** or **IOCCC submit server** is not ready).

In a number of cases, an HTML comment with a **XXX** inside,
was added as an indicator for the need of a future edit.

Added `make sitemap` as an alias for `make gen_sitemap`.

Performed `make gen_top_html sitemap` to do perform the above.

Makefile

@@ -240,7 +240,7 @@ indent.c:
 
 .PHONY: help genpath genfilelist verify_entry_files gen_authors gen_location gen_years \
 	entry_index gen_top_html gen_status thanks gen_other_html quick_entry_index \
-	gen_year_index quick_www www gen_sitemap \
+	gen_year_index quick_www www gen_sitemap sitemap \
 	form_entry_tarball form_year_tarball form_all_tarball tar
 
 # Suggest rules in this section
@@ -401,7 +401,7 @@ quick_entry_index quick_readme2index: ${ALL_RUN} ${QUICK_README2INDEX}
 
 # generate the XML sitemap
 #
-gen_sitemap: ${GEN_SITEMAP}
+gen_sitemap sitemap: ${GEN_SITEMAP}
 	@echo '=-=-=-=-= IOCCC begin make $@ =-=-=-=-='
 	${GEN_SITEMAP} -v 1
 	@echo '=-=-=-=-= IOCCC complete make $@ =-=-=-=-='