exclude sitemap, css and 404 from sitemap

Signed-off-by: Jess Frazelle <acidburn@google.com>

404.md

@@ -2,6 +2,7 @@
 layout: docwithnav
 title: 404 Error!
 permalink: /404.html
+no_canonical: true
 ---
 
 <script src="/js/redirects.js"></script>

robots.txt

@@ -3,5 +3,7 @@ User-agent: *
 Disallow: /legacy/
 Disallow: /v1.0/
 Disallow: /v1.1/
+Disallow: /404/
+Disallow: 404.html
 
 SITEMAP: http://kubernetes.io/sitemap.xml

sitemap.xml

@@ -11,8 +11,8 @@
   <loc>http://kubernetes.io/</loc>
   <lastmod>{{ site.time | date_to_xmlschema }}</lastmod>
 </url>
-{% for page in site.pages %}<url>
+{% for page in site.pages %}{% if page.url != "/404.html" and page.url != "/sitemap.xml" and page.url != "/css/styles.css" %}<url>
   <loc>http://kubernetes.io{{ page.url }}</loc>
   <lastmod>{% if page.date %}{{ page.date | date_to_xmlschema }}{% else %}{{ site.time | date_to_xmlschema }}{% endif %}</lastmod>
-</url>{% endfor %}
+</url>{% endif %}{% endfor %}
-</urlset>
+</urlset>