Fix and finish help text

dotfiles/imapdomo/utils/imapdomo

@@ -5,15 +5,25 @@
 shellfu import pretty
 
 usage() {
-    mkusage "newmail" \
-            "rewind" \
-            "cleanup" \
-            "migrate" \
-         -- "newmail - check for and file new mail" \
-            "rewind - re-add messages from FILTER_FAIL back" \
-            "       to FILTER_QUEUE" \
-            "cleanup - delete or archive old messages" \
-            "migrate - move mail between mailboxes"
+    mkusage "[options] ACTION" \
+        -o                                                                    \
+            "-c DIR      change to DIR before doing anything"                 \
+            "-d          turn on debugging mode"                              \
+       --                                                                     \
+       "imapdomo will try to read .imapdomo/host/HOSTNAME/init.lua and"       \
+       ".imapdomo/host/HOSTNAME/handlers/ACTION.lua, where HOSTNAME is your"  \
+       "short hostname (eg. 'foo' in 'foo.example.com')."                     \
+       ""                                                                     \
+       "four valid actions are understood; since you must write handler for"  \
+       "each action you want to use, the meanings below are purely a guide:"  \
+       ""                                                                     \
+       "    newmail - check for and file new mail"                            \
+       "    rewind  - re-add messages from FILTER_FAIL back to FILTER_QUEUE"  \
+       "    cleanup - delete or archive old messages"                         \
+       "    migrate - move mail between mailboxes"                            \
+       ""                                                                     \
+       "See imapfilter_config(5)) for guide and API reference.  Few functions"\
+       "are also available in .imapdomo/common.lua"
 }
 
 mkcmd() {