Adding support for opensearch of documentation (#38593)

docs/docsite/_static/opensearch.xml

@@ -0,0 +1,9 @@
+<OpenSearchDescription xmlns="http://a9.com/-/spec/opensearch/1.1/"
+                       xmlns:moz="http://www.mozilla.org/2006/browser/search/">
+  <ShortName>Ansible</ShortName>
+  <Description>Search Ansible Documentation</Description>
+  <InputEncoding>UTF-8</InputEncoding>
+  <Image width="16" height="16" type="image/x-icon">https://docs.ansible.com/favicon.ico</Image>
+  <Url type="text/html" method="get" template="https://docs.ansible.com/ansible/latest/search.html?q={searchTerms}&amp;ref=opensearch"/>
+  <moz:SearchForm>https://docs.ansible.com/ansible/latest/search.html</moz:SearchForm>
+</OpenSearchDescription>

docs/docsite/rst/conf.py

@@ -183,7 +183,7 @@ html_copy_source = False
 # If true, an OpenSearch description file will be output, and all pages will
 # contain a <link> tag referring to it.  The value of this option must be the
 # base URL from which the finished HTML is served.
-# html_use_opensearch = ''
+html_use_opensearch = 'https://docs.ansible.com/ansible/latest/'
 
 # If nonempty, this is the file name suffix for HTML files (e.g. ".xhtml").
 # html_file_suffix = ''