Update the README for the move to Xilem

README.md

@@ -1,5 +1,18 @@
+> [!Important]
+> Masonry has been moved into the [Xilem](https://github.com/linebender/xilem/tree/main/masonry) repository.
+> It can be found in the `masonry` folder at the root in that repository, which in turn can be found at <https://github.com/linebender/xilem/>.
+> This repository may be useful for exploring the history of Masonry.
+>
+> The version of Masonry in that repository is now also [published](https://crates.io/crates/masonry) on crates.io.
+
 ## Masonry
 
+> [!Caution]
+> **This README is outdated.**
+>
+> See the info box above for more details.
+> The previous README is included for historical reference.
+
 Masonry is a framework that aims to provide the foundation for Rust GUI libraries.
 
 Masonry gives you a platform to create windows (using [Glazier](https://github.com/linebender/glazier) as a backend) each with a tree of widgets. It also gives you tools to inspect that widget tree at runtime, write unit tests on it, and generally have an easier time debugging and maintaining your app.
@@ -8,7 +21,7 @@ The framework is not opinionated about what your user-facing abstraction will be
 
 This project was originally a fork of [Druid](https://github.com/linebender/druid) that emerged from discussions I had with Raph Levien and Colin Rofls about what it would look like to turn Druid into a foundational library.
 
-## Installing
+<!-- ## Installing
 
 ```sh
 cargo add masonry
@@ -22,9 +35,10 @@ On Linux, Masonry requires gtk+3; see [GTK installation page](https://www.gtk.or
 ### OpenBSD
 
 On OpenBSD, Masonry requires gtk+3; install from packages:
+
 ```sh
 pkg_add gtk+3
-```
+``` -->
 
 ## Example
 
@@ -96,7 +110,6 @@ This simplicity makes Masonry somewhat painful if you want to use it to actually
 
 (Well, in theory. The first stress-test will be porting [Panoramix](https://github.com/PoignardAzur/panoramix), a React-style GUI in Rust, to Masonry.)
 
-
 ## Unit tests
 
 Masonry is designed to make unit tests easy to write, as if the test function were a mouse-and-keyboard user. Tests look like this:
@@ -136,9 +149,9 @@ fn some_test_with_a_button() {
 }
 ```
 
-## Contributing
+<!-- ## Contributing
 
-Issues and PRs are welcome. See [`help-wanted` issues](https://github.com/PoignardAzur/masonry-rs/issues?q=is%3Aissue+is%3Aopen+label%3A%22help+wanted%22) if you don't know where to begin.
+Issues and PRs are welcome. See [`help-wanted` issues](https://github.com/PoignardAzur/masonry-rs/issues?q=is%3Aissue+is%3Aopen+label%3A%22help+wanted%22) if you don't know where to begin. -->
 
 ## Roadmap