t/README: mention test files are make targets
Since
23fc63bf8f (make tests ignorable with "make -i", 2005-11-08), each
test file defines a target in the test Makefile, such that one can
invoke:
make *checkout*
to run all tests with 'checkout' in their filename. This is useful to
run a subset of tests when you have a good idea of what part of the code
is touched by the changes your are testing.
Document that in t/README to help new (or more seasoned) contributors
that might not be aware.
Signed-off-by: Philippe Blain <levraiphilippeblain@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>