Improve formatting of mdoc

https://github.com/jgm/pandoc/issues/9201 has been fixed, so we can now
go through 'man' instead.

Makefile

@@ -141,16 +141,16 @@ ${CHANGES_MD}: dat/%.md: dat/%.log mkchangelog.pl
 
 
 # pandoc doesn't support mdoc directly. Going through a `mandoc -T man` tends
-# to generate nicer formatting, but runs into another issue:
-# https://github.com/jgm/pandoc/issues/9201
-# We'll have to settle for the quote-abusing `mandoc -T markdown` with some
-# post-processing and fixups.
+# to generate nicer formatting than `mandoc -T markdown`, though any links
+# appear to get lost. Going through `mandoc -T html` is also an option, but
+# pandoc makes quite a mess of that.
 ${MDOC_MD}: dat/%.md: dat/%.mdoc
 	@echo "MDOC   $*"
 	@(echo "% ${shell for i in ${PAGES}; do case "$$i" in "$*.mdoc "*) echo "$$i" | sed -E 's/[^ ]+ +[^ ]+ +//';; esac; done}";\
-		mandoc -T markdown "$<" | \
-		tail -n +2 | head -n -2 | \
-		sed -E -e 's/-&#45;/\\--/g' -e 's/&#45;/-/g' -e 's/(^|[ ,.])([a-zA-Z0-9-]+)\(([1-8])\)/\1[\2(\3)](https:\/\/manned.org\/man\/\2.\3)/g' \
+		mandoc -T man "$<" |\
+		pandoc -f man -t markdown |\
+		sed -E -e 's/(^|[ ,.])([a-zA-Z0-9-]+)\(([1-8])\)/\1[\2(\3)](https:\/\/manned.org\/man\/\2.\3)/g' \
+		       -e 's/\*\*(https:[^[:space:]]+)\*\*/[\1](\1)/g' \
 		) >"$@"