Documentation: dev-tools: Clarify requirements for result description

Currently the KTAP specification says that a test result line is

  <result> <number> [<description>][ # [<directive>] [<diagnostic data>]]

and the description of a test can be "any sequence of words
(can't include #)" which specifies that there may be more than
one word but does not specify anything other than those words
which might be used to separate the words which probably isn't
what we want.  Given that practically we have tests using a range
of separators for words including combinations of spaces and
combinations of other symbols like underscores or punctuation
let's just clarify that the description can contain any character
other than # (marking the start of the directive/diagnostic) or
newline (marking the end of this test result).

Signed-off-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: David Gow <davidgow@google.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>