Add anvil to the readme

README.md

@@ -4,7 +4,7 @@
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 A smithy for rusty wayland compositors
 
@@ -16,9 +16,31 @@ functionnalities that pretty much any compositor will need, in a generic fashion
 
 Also:
 
+- **Documented:** Smithay strives to maintain a clear and detailed documentation of its API and its
+  functionnalities. Compiled documentations are available on [docs.rs](https://docs.rs/smithay) for released
+  versions, and [here](https://smithay.github.io/smithay) for the master branch.
 - **Safety:** Smithay will target to be safe to use, because Rust.
 - **Modularity:** Smithay is not a framework, and will not be constraining. If there is a
   part you don't want to use, you should not be forced to use it.
 - **High-level:** You should be able to not have to worry about gory low-level stuff (but 
   Smithay won't stop you if you really want to dive into it).
 
+## Anvil
+
+Like others, Smithay as a compositor library has its own sample compositor: anvil.
+
+You can run it with cargo after having cloned this repository:
+
+```
+cargo run -p anvil -- --{backend}
+```
+
+The currently available backends are:
+
+- `--winit`: start anvil as a [Winit](https://github.com/tomaka/winit) application. This allows you to run it
+  inside of an other X11 or Wayland session.
+- `--tty-udev`: start anvil in a tty with udev support. This is the "traditional" launch of a Wayland
+  compositor. Note that this requires you to start anvil as root if your system does not have logind
+  available ([consolekit support is planned](https://github.com/Smithay/smithay/issues/95)).
+- `--tty-raw`: start anvil without udev support, manually binding all ressources. Requires to be run as root.
+  This backend is mostly present as example code for use in very minimalistic systems.