[PATCH v2 22/28] buildman: Add the abbreviation for --boards

[sjg at google.com]

This option may be frequency used, so mention that it can be abbreviated
to --bo

Signed-off-by: Simon Glass <sjg at chromium.org>
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Changes in v2: None

 tools/buildman/README | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

Applied to u-boot-dm, thanks!