add sitemap and robots.txt

requirements.txt

@@ -31,3 +31,4 @@ sphinxcontrib-serializinghtml==1.1.3
 tornado==6.0.3
 urllib3==1.25.3
 watchdog==0.9.0
+sphinx-sitemap==2.2.0

source/conf.py

@@ -130,3 +130,6 @@ html_js_files = [
     'js/readmore.js',
     'js/baidutongji.js',
 ]
+
+html_baseurl = 'http://golang.iswbm.com'
+html_extra_path = ["robots.txt"]

source/robots.txt

+User-agent: *
+Sitemap: http://golang.iswbm.com/sitemap.xml