Is it a good idea to add a "Procedural helpers" section in the docs that outlines all the helpers? This would allow someone to quickly see them in one place.
There's no reason for that, they're already documented with the classes they provide shortcuts for. There's no reason to search for "procedural helpers", you're not going to use something because its got a procedural helper. But as it's documented with the class to which it belongs you will find it when you actually need it.
Ok cool. I just asked because I had to do some code searching to remember how e(), or __(), was used in the core. Maybe, an alternative would be a simple docs search feature; although tougher to implement without a backend server.