docs: fix broken community banner

website/docs/community/index.mdx

@@ -25,8 +25,8 @@ import Link from "@docusaurus/Link";
           <ThemedImage
             alt="Banner of cybozu developer community"
             sources={{
-              light: 'https://global.discourse-cdn.com/business4/uploads/cybozu/original/1X/46b6b48c317c045917e2c184e7f69db295b8768a.png',
-              dark: 'https://global.discourse-cdn.com/business4/uploads/cybozu/original/1X/a23252a53e760371071afb6c607f8b96d9dc2edf.png',
+              light: require("@site/static/img/cybozu-developer-community.png").default,
+              dark: require("@site/static/img/cybozu-developer-community-dark.png").default,
             }}
           />
         </Link>
@@ -36,8 +36,8 @@ import Link from "@docusaurus/Link";
           <ThemedImage
             alt="Banner of kintone developer forum"
             sources={{
-              light: 'https://global.discourse-cdn.com/standard17/uploads/kintone/original/1X/22edf6309a55df93b0e1c1a0bc76e9a632aad507.png',
-              dark: 'https://global.discourse-cdn.com/standard17/uploads/kintone/original/1X/ea7860dd7df008122e858768c806501321c2ef8e.png',
+              light: require("@site/static/img/kintone-developer-forum.png").default,
+              dark: require("@site/static/img/kintone-developer-forum-dark.png").default,
             }}
           />
         </Link>