keys2doc: fix handling of dots (.) in description list term

Quote character keybindings to workaround unescaped (resulting to
invisible) dots in elinkskeys(5).
(cherry picked from commit 3de420d72f)

doc/tools/keys2doc

@@ -82,6 +82,7 @@ print_keymap_defaults()
 		# there the "read" command consumes the backslashes.)
 		action=$(grep " $action," "$CONFIGDIR/actions-$keymap.inc" \
 			| sed "s/.*\"\([^\"]*\)\".*N__(\"\(.*\)\").*/\2 ('\1')/;s/\\\\\"/\"/g")
+		q=
 
 		case "$key" in
 		KBD_*)
@@ -95,6 +96,7 @@ print_keymap_defaults()
 		*)
 			key=$(echo "$key" | sed "s/^'\(.*\)'$/\1/" \
 			    | sed "s/'/{squote}/")
+			q='"'
 			;;
 		esac
 
@@ -106,7 +108,7 @@ print_keymap_defaults()
 		esac
 
 		echo 'ifdef::backend-docbook[]'
-		echo "'$modifier$key'::"
+		echo "'$modifier$q$key$q'::"
 		echo "	$action"
 		echo
 		echo 'endif::backend-docbook[]'