LU-16382 spec: improve Summary and description.

LU-16382 spec: improve Summary and description.

Summary should not repeat the name of the package, and should avoid
being overly long.  It should start with CAPS and not end with period.

Description should be more detailed than the summary.

Test-Parameters: trivial
Signed-off-by: Mr NeilBrown <neilb@suse.de>
Change-Id: Ifcdb881f649200e1857c707fb2c589579e4035a4
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/49367
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>
Reviewed-by: Jian Yu <yujian@whamcloud.com>
Reviewed-by: jsimmons <jsimmons@infradead.org>