more doc

src/macros.rs

@@ -1,3 +1,19 @@
+
+/// Create a `HashMap` from a shorthand notation.
+///
+/// ```
+/// #[macro_use]
+/// extern crate ureq;
+///
+/// fn main() {
+/// let headers = map! {
+///     "X-API-Key" => "foobar",
+///     "Accept" => "application/json"
+/// };
+///
+/// let agent = ureq::agent().set_map(headers).build();
+/// }
+/// ```
 #[macro_export]
 macro_rules! map(
     { $($key:expr => $value:expr),* } => {