fix: copy README to npm directory for npmjs display

Author: tae2089

.github/workflows/release.yml

@@ -129,6 +129,9 @@ jobs:
           node-version: '20'
           registry-url: 'https://registry.npmjs.org'
 
+      - name: Copy README for npm
+        run: cp README.md npm/README.md
+
       - name: Set version from tag
         run: |
           VERSION=${GITHUB_REF#refs/tags/v}