Add documentation about partial application

README.md

@@ -11,3 +11,17 @@ To setup the dotfiles:
 
 1. `git clone https://github.com/hakoerber/dotfiles.git ~/dotfiles`
 2. `cd ~/dotfiles && ./bootstrap.sh`
+
+# Partial application
+
+To apply only a subset of the changes, use ansible tags that are available via
+the Makefile:
+
+| Command | Description |
+| --- | --- |
+| `make update` | Updates the system with the latest packages |
+| `make packages` | Installs all defined packages (see `packages.yml`) |
+| `make dotfiles` | Manages the users' dotfiles |
+
+Note that these are not supported on a first bootstrap run. Only use them after
+the bootstrap to update existing configuration.