docs: differentiate fn s from macro s

src/experimental/to_string.rs

@@ -2,11 +2,16 @@
 #![allow(unused)]
 
 /// Converts the parameter into a [String] using the [Into] trait.
+///
+/// Requires parameter to implement a [From] or [Into] trait to allow it be transformed.
 pub fn s(v: impl Into<String>) -> String {
     v.into()
 }
 
 /// Converts the parameter into a [String] by calling `.to_string()`.
+///
+/// Unlike the [s] function, the value only need to have a [to_string] method. Preusmably it will
+/// return a [String], but this macro doesn't make that gaurantee.
 #[macro_export]
 macro_rules! s {
     ($value:expr) => {