Add Tailwind info to README

README.md

@@ -57,6 +57,15 @@ manual LDIF imports etc. (or provide a staging instance)
 * [Ruby on Rails](https://guides.rubyonrails.org/)
 * [Sass](https://sass-lang.com/documentation)
 
+### Front-end
+
+* [Tailwind CSS](https://tailwindcss.com/)
+
+**Caveat:** if you only add Tailwind classes/directives to templates or
+helpers, but there's no change in the stylesheet files, then the new directives
+won't be compiled in production. In this case, count up the version comment at
+the top of `app/javascript/stylesheets/application.scss` to trigger compilation.
+
 ### Testing
 
 * [RSpec](https://rspec.info/documentation/)