Suggest prove6 over prove

doc/Language/testing.pod6

@@ -68,11 +68,27 @@ command line:
 =for code :lang<shell>
 $ perl6 t/test-filename.t
 
-Or via the L<prove|https://perldoc.perl.org/prove.html> command from Perl 5,
-where using C<--exec> to specify the executable that runs the tests:
+To run all tests in the directory recursively,
+L<prove6|https://modules.perl6.org/dist/App::Prove6> application can
+be used.
+
+You have to install it before using with zef:
+
+=for code :lang<shell>
+$ zef install App::Prove6
+
+You can run C<prove6> in a distribution directory this way:
 
 =for code :lang<shell>
-$ prove --exec perl6 -r t
+$ prove6 --lib t/
+
+The C<t/> argument specified directory that contains tests and the
+C<--lib> option is passed to include C<lib> directory into Perl 6
+distribution path, it is an equivalent of C<-Ilib> argument of
+C<perl6> command.
+
+For more documentation regarding C<prove6> usage refer to L<its
+page|https://modules.perl6.org/dist/App::Prove6>.
 
 To abort the test suite upon first failure, set the
 C<PERL6_TEST_DIE_ON_FAIL> environmental variable: