docs: announce the end of support

bajtos · bajtos · commit 81bc5be02a1e · 2025-06-23T09:33:38.000+02:00
Signed-off-by: Miroslav Bajtoš &lt;oss@bajtos.net&gt;
diff --git a/README.md b/README.md
@@ -10,6 +10,9 @@ rusty-lassie
 
 Lassie repository: https://github.com/filecoin-project/lassie
 
+> [!CAUTION]
+> **This crate is no longer mantained.**
+
 ## Installation
 
 ```shell
