perf tests shell kprobes: Add missing description as used by 'perf test' output

Before:

root@x1:~# perf test 76
76: SPDX-License-Identifier: GPL-2.0 : Ok
root@x1:~#

After:

root@x1:~# perf test 76
76: Add 'perf probe's, list and remove them. : Ok
root@x1:~#

Reviewed-by: Ian Rogers <[e-mail]>
Cc: Adrian Hunter <[e-mail]>
Cc: Athira Rajeev <[e-mail]>
Cc: Jiri Olsa <[e-mail]>
Cc: Kajol Jain <[e-mail]>
Cc: Michael Petlan <[e-mail]>
Cc: Namhyung Kim <[e-mail]>
Cc: Veronika Molnarova <[e-mail]>
Link: https://lore.kernel.org/lkml/ZigRDKUGkcDqD-yW@x1
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/tests/shell/base_probe/test_adding_kernel.sh

···
 #!/bin/bash
+# Add 'perf probe's, list and remove them
 # SPDX-License-Identifier: GPL-2.0
 
 #