Be more informative about saturnin__runhook()

src/saturnin.sh.skel

 
 saturnin__runhook() {
     #
-    # Run custom hook
+    # Run custom hook named $1 from respective configuration section
+    #
+    # Will load joined multi-line key "hook.$SATURNIN_SUBCOMMAND.$1",
+    # and execute it as Bash code.
     #
     local hname="$1"
     local hook_code