Release docs 20.0.0

[assignUser]

No description provided.

[amoeba]

Thanks! This still has the issue we hadn't fixed involving the warning banner. On the stable docs in this PR, the <script> tag is still,

<script>
    DOCUMENTATION_OPTIONS.theme_version = '0.16.1';
    DOCUMENTATION_OPTIONS.theme_switcher_json_url = '/docs/_static/versions.json';
    DOCUMENTATION_OPTIONS.theme_switcher_version_match = '';
    DOCUMENTATION_OPTIONS.show_version_warning_banner =
        true;   <---- this should be false but our script doesn't catch it with the 
</script>

We should change it to,

    <script>
        DOCUMENTATION_OPTIONS.theme_version = '0.16.1';
        DOCUMENTATION_OPTIONS.theme_switcher_json_url = '/docs/_static/versions.json';
        DOCUMENTATION_OPTIONS.theme_switcher_version_match = '';
        DOCUMENTATION_OPTIONS.show_version_warning_banner = false;
        </script>

before we merge this.

[amoeba]

Looks good now, tested locally. Thanks.