t/README: change "Inside <X> part" to "Inside the <X> part"

Change the mention of "Inside the <script> part, the standard
output..." to use the definite article, which makes more sense in this
context.

This changes documentation I originally added back in commit
20873f4 ("t/README: Document the do's and don'ts of tests",
2010-07-02).

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Author: avar

t/README

@@ -477,7 +477,7 @@ Don't:
 
 Keep in mind:
 
- - Inside <script> part, the standard output and standard error
+ - Inside the <script> part, the standard output and standard error
    streams are discarded, and the test harness only reports "ok" or
    "not ok" to the end user running the tests. Under --verbose, they
    are shown to help debugging the tests.