[io grant] Improve IO::Handle.t docs

Author: zoffixznet

doc/Type/IO/Handle.pod6

@@ -511,9 +511,10 @@ Returns C<True> if the handle is open.
 
 Defined as:
 
-    method t(IO::Handle:D: --> Bool)
+    method t(IO::Handle:D: --> Bool:D)
 
-Returns C<True> if the handle is opened to a tty.
+Returns C<True> if the handle is opened to a
+L<TTY|https://en.wikipedia.org/wiki/Terminal_emulator>, C<False> otherwise.
 
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