Add plugin documentation

README.md

@@ -1,7 +1,9 @@
 # Decman
 
+> THIS README IS FOR AN UNRELEASED VERSION!
+>
 > There are going to be breaking changes!
-> Decman has undergone an architecture rewrite! The new architecture makes decman more expandable and maintainable.
+> Decman has undergone an architecture rewrite. The new architecture makes decman more expandable and maintainable.
 >
 > The AUR package will receive this update after I have tested it enough.
 > See this [tag](https://github.com/kiviktnm/decman/tree/0.4.2) for the current version of decman available in the AUR.
@@ -12,8 +14,6 @@ Decman is a declarative package & configuration manager for Arch Linux. It allow
 
 ## Overview
 
-[See the complete documentation for using decman.](/docs/README.md)
-
 To use decman, you need a source file that declares your system installation. I recommend you put this file in source control, for example in a git repository.
 
 `/home/user/config/source.py`:
@@ -124,6 +124,8 @@ Decman has some CLI options, to see them all run:
 decman --help
 ```
 
+[See the complete documentation for using decman.](/docs/README.md)
+
 ## Installation
 
 Clone the decman PKGBUILD:
@@ -213,7 +215,7 @@ import decman
 decman.systemd.enabled_units |= {"NetworkManager.service"}
 
 # User specific units
-decman.systemd.enabled_user_units.setdefault("user", {}).update({"syncthing.service"})
+decman.systemd.enabled_user_units.setdefault("user", set()).update({"syncthing.service"})
 ```
 
 ### Flatpak
@@ -263,16 +265,24 @@ Note that `files` is not a plugin, but is defined here anyways.
 Before the core execution order, decman will run hook methods from `Module`s.
 
 1. `before_update`
-1. `on_disable`
+2. `on_disable`
 
 After the plugin execution, decman will run the following hook methods.
 
 1. `on_enable`
-1. `on_change`
-1. `atfer_update`
+2. `on_change`
+3. `atfer_update`
 
 Operations and hooks may be skipped with command line options.
 
+```sh
+# Skip the aur plugin
+sudo decman --skip aur
+
+# Only apply file operations
+sudo decman --no-hooks --only files
+```
+
 ## Why use decman?
 
 Here are some reasons why I created decman for myself.