fix typo in misskey.nginx (#5445)

sites-ebabled => sites-enabled

docs/examples/misskey.nginx

 # Sample nginx configuration for Misskey
 #
 # 1. Replace example.tld to your domain
-# 2. Copy to /etc/nginx/sites-available/ and then symlink from /etc/nginx/sites-ebabled/
+# 2. Copy to /etc/nginx/sites-available/ and then symlink from /etc/nginx/sites-enabled/
 #    or copy to /etc/nginx/conf.d/
 
 # For WebSocket