Phobos, minimal runtime, -betterC compatibility documentation

[Arun Chandrasekaran]

I'm more interested in no/minimal runtime[1] than -betterC for my 
use cases.

I think it will be good to have the document mention if the 
function is supported without the druntime and/or with -betterC. 
This documentation can be the module level or function level. Is 
this possible and/or is it worth it?

I understand that using druntime function with -betterC will make 
the compiler throw error. But it will be good to know it up front 
via doc if a function uses druntime or not.

[1] https://dlang.org/changelog/2.079.0.html#minimal_runtime