some docs

src/utils/gen_util.rs

@@ -201,6 +201,19 @@ pub fn partial_ordering_desc<T: PartialOrd>(a: T, b: T) -> Ordering {
     partial_ordering(a, b).reverse()
 }
 
+/// Checks that the first string is equal to any of the other ones in a ASCII case-insensitive match.
+///
+/// The generated code is the same as writing:
+/// `to_ascii_lowercase(a) == to_ascii_lowercase(b) || to_ascii_lowercase(a) == to_ascii_lowercase(c)`,
+/// but without allocating and copying temporaries.
+///
+/// # Examples
+///
+/// ```no_run
+/// assert!(multi_eq_ignore_ascii_case!("test", "test"));
+/// assert!(multi_eq_ignore_ascii_case!("test", "a" | "b" | "test"));
+/// assert!(!multi_eq_ignore_ascii_case!("test", "a" | "b" | "c"));
+/// ```
 #[macro_export]
 macro_rules! multi_eq_ignore_ascii_case {
     ( $lhs:expr, $last:literal ) => {