chore: update readme

Author: rdlabo

README.md

@@ -41,6 +41,8 @@ This is a CSS theme for extending your Ionic project. It does not work on its ow
 npm install @rdlabo/ionic-theme-md3
 ```
 
+Note: **If you use @ionic/core@ < 8.8.0**, use @rdlabo/ionic-theme-md3@1.0.2.
+
 And import the theme in your project's main CSS file (e.g., `src/styles.scss`).
 
 ```css

package.json

@@ -55,6 +55,6 @@
     "typescript": "^5.9.3"
   },
   "peerDependencies": {
-    "@ionic/core": "> 8.0.0"
+    "@ionic/core": ">= 8.8.0"
   }
 }