Improve Flow scraper entry classification

Closes #680.

lib/docs/filters/flow/entries.rb

@@ -6,6 +6,7 @@ module Docs
       end
 
       def get_type
+        return 'React' if slug.start_with?('react')
         type = at_css('.guide-nav .nav-item').content.strip
         type.remove! %r{ \(.*}
         type