docs: convention for usage documentation.

.config/fish/functions/dot.fish

@@ -98,17 +98,19 @@ end
 # named after that function; a shared helper would go undefined if `dot help`
 # ran in a completion context before `dot` itself had ever been sourced.
 function __dot_help
-    echo "dot: manage dotfiles via a bare repo checked out over \$HOME"
-    echo
-    echo "Commands:"
-    echo "  init    bootstrap the dotfiles repo on a new machine"
-    echo "  help    show this message"
+    echo "dot: manage dotfiles via a bare repo checked out over \$HOME
+
+Commands:
+  init    bootstrap the dotfiles repo on a new machine
+  help    show this message"
 
     for f in $HOME/.config/dot/commands/*.fish
         test -e $f; or continue
         echo "  "(path basename $f | path change-extension '')
     end
 
-    echo
-    echo "Any other command is passed through to git (dot status, dot add, dot commit, dot push, ...)."
+    echo "
+Run 'dot <command> help' for flags on a specific command.
+
+Any other command is passed through to git (dot status, dot add, dot commit, dot push, ...)."
 end