Mention wrapping in contributing docs

docs/src/faq/contributing.md

@@ -38,6 +38,10 @@ skip the first two steps.
 2. Create high-level Julia structures and functionality
 3. Create tests for added functionality
 
+`struct`s and `enums` for Objective-C interfaces are automatically generated (see res/wrap/),
+so you should not have to define them. If using a struct for the first time in a higher-level
+interface, remember to add tests! You may need to define more functions around the structs.
+
 ## Mapping to Metal Intrinsics
 
 Some Metal functions map directly to Apple intermediate representation intrinsics. In this
@@ -134,4 +138,4 @@ their free time helping out. Most anything you're able to do is helpful, but if
 stuck, seek guidance from Slack or Discourse. Don't feel like your contribution has to be
 perfect. If you put in effort and make progress, there will likely be some senior developer
 willing to polish your code before merging. Open-source software is a team effort...welcome
-to the team!
+to the team!

res/wrap/README.md

@@ -2,11 +2,11 @@
 
 This directory contains scripts to generate Julia wrappers for Metal and MetalPerformanceShaders.
 
-Currently, only `enums` and `structs` are able to be generated.
+Currently, only `enums` and `structs` are able to be generated. Don't forget to update the wrappers section in the contributing docs if this changes!
 
 The scripts are meant to be run from this directory, and at the moment, [this Clang.jl branch](https://github.com/christiangnrd/Clang.jl/tree/objectiveC) must be used.
 
-####
+--------
 
 Comment from removed file on `MTLDataType`. Parsing the headers does not reveal these hidden values.