I think I found the answers I need here:
[https://github.com/nim-lang/nimble#project-structure](https://github.com/nim-lang/nimble#project-structure)
In case anyone else finds this with a search, this worked:
# Package
version = "0.1.0"
author = "Jack Mott"
description = "type safe opengl wrapper"
license = "MIT"
srcDir = "src"
# Dependencies
requires "nim >= 0.17.0"
requires "sdl2"
requires "opengl"
requires "stb_image"
task hello_triangle, "Runs hello triangle":
exec "nim c -r examples/hello_triangle"
task shaders, "Runs shaders":
exec "nim c -r examples/shaders"