Fix --which treated as if no value was needed

src/bin/sfdoc

@@ -12,7 +12,7 @@ usage() {
         "[options] MODULE"                                              \
         "[options] --ls [MODULE]"                                       \
         "[options] --ls{var|fun} MODULE"                                \
-        "[options] --which"                                             \
+        "[options] --which MODULE"                                      \
         "[options] --lsmod"                                             \
         "[options] -s|--src MODULE"                                     \
         "[options] --export FMT MODULE"                                 \
@@ -120,7 +120,7 @@ main() {
     debug -v SHELLFU_INCLUDE SHELLFU_PATH SFDOC_SHOW_HIDDEN
     debug -v action format module RealModuleName
     case $action:$mspec in
-        lsx:*|lsm:*|wch:*) true ;;
+        lsx:*|lsm:*)    true ;;
         *:)             usage -w "no MODULE?" ;;
     esac
     case $spectype in