Disable machine translation. (#3703)

Author: hsubox76

scripts/docgen/theme/layouts/default.hbs

@@ -6,6 +6,7 @@
     <meta name="hide_page_heading" value="true" />
     <meta name="project_path" value="/_project.yaml" />
     <meta name="book_path" value="/docs/reference/_book.yaml" />
+    <meta name="translation" value="disabled" />
     <title>{{#ifCond model.name '==' project.name}}{{project.name}}{{else}}{{model.name}} | {{project.name}}{{/ifCond}}</title>
     <meta name="description" content="Reference for {{model.name}}">
     <meta name="viewport" content="width=device-width, initial-scale=1">