docs: add minimu system libzstd library version to README.md

kjdev · kjdev · commit c6b079e85552 · 2025-06-10T09:42:44.000+09:00
diff --git a/README.md b/README.md
@@ -25,6 +25,8 @@ To use the system library
 % ./configure --with-libzstd
 ```
 
+> minimum system libzstd library version to 1.4.0
+
 Install from [pecl](https://pecl.php.net/package/zstd):
 
 ``` bash
