fix(docs): remove missing favicon reference

Docusaurus config referenced img/favicon.ico which doesn't exist in
static/img/. Removing the line lets Docusaurus fall back to its default
favicon rather than serving a broken asset reference.

https://claude.ai/code/session_011UQT9Yu7T3U3393WiDXemb

Author: claude

docs/docusaurus.config.ts

@@ -5,8 +5,6 @@ import type * as Preset from '@docusaurus/preset-classic';
 const config: Config = {
   title: 'Game Server Deploy',
   tagline: 'Cost-efficient multi-game dedicated server platform on AWS Fargate',
-  favicon: 'img/favicon.ico',
-
   url: 'https://codercoco.github.io',
   baseUrl: '/game-server-deploy/',