add todo

Author: bcumming

todo.md

@@ -0,0 +1,25 @@
+Create some example recipes that exercise all workflows.
+
+For each example recipe
+- `compilers/*/packges.yaml` and `environments/*/packges.yaml` are generated correctly
+- `config/*.yaml` are generated correctly
+- `modules` are generated correctly
+- compilers are correctly linked into the views
+- the correct default compiler is set
+- iterative builds don't break unreasonable
+
+To consider:
+- test on systems where gcc 7.5.0 is the only available option
+- user overriding gcc in `recipe/packages.yaml`
+- 
+
+## Examples
+
+prgenv-gnu:
+- only use gcc
+
+prgenv-nvhpc
+- use gcc and nvhpc
+
+prgenv-llvm
+- a stretch goal