[io grant] Document IO::Spec::Unix.basename

Author: zoffixznet

doc/Type/IO/Spec/Unix.pod6

@@ -22,6 +22,17 @@ need to use C<IO::Spec::*>. Use L«C<IO::Path>|/type/IO::Path» instead.
 Returns a string that represents C<$path>, but relative to C<$base> path.
 Both C<$path> and C<$base> may be relative paths C<$bar> defaults to C<$*CWD>
 
+=head2 method basename
+
+    method basename(Str:D $path --> Str:D)
+
+Takes a path as a string and return a possibly-empty portion after the last
+slash:
+
+    IO::Spec::Unix.basename("foo/bar/") .perl.say; # OUTPUT: «""␤»
+    IO::Spec::Unix.basename("foo/bar/.").perl.say; # OUTPUT: «"."␤»
+    IO::Spec::Unix.basename("foo/bar")  .perl.say; # OUTPUT: «"bar"␤»
+
 =head2 method tmpdir
 
 Defined as: