Add extreme inpuit for the secondary branch: W_-1(-1e-308)

src/lib.rs

@@ -71,18 +71,20 @@ assert_abs_diff_eq!(mln4, -f32::ln(4.0));
 "##
 )]
 //!
-//! The implementation can handle massive inputs just as well:
+//! The implementation can handle extreme inputs just as well:
 //!
 #![cfg_attr(
     feature = "50bits",
     doc = r#"
 ```
 # use approx::assert_relative_eq;
-use lambert_w::lambert_w0;
+use lambert_w::{lambert_w0, lambert_wm1};
 
 let big = lambert_w0(f64::MAX);
+let tiny = lambert_wm1(-1e-308);
 
 assert_relative_eq!(big, 703.2270331047702, max_relative = 1e-15);
+assert_relative_eq!(tiny, -715.7695669234213, max_relative = 1e-15);
 ```
 "#
 )]