doc: fix location of Automake's own test-suite.log file * doc/automake.texi (Reporting Bugs): The global testsuite log of Automake is now (basically since we have removed make recursion from the Automake's build system) saved in the file 'test-suite.log', not in the file 'tests/test-suite.log'. Adjust accordingly. Signed-off-by: Stefano Lattarini <stefano.lattarini@gmail.com>