security/smack/smackfs: small kernel-doc fixes

security/smack/smackfs: small kernel-doc fixes

Add function short descriptions to the kernel-doc where missing.
Correct a verb and add ending periods to sentences.

smackfs.c:1080: warning: missing initial short description on line:
 * smk_net4addr_insert
smackfs.c:1343: warning: missing initial short description on line:
 * smk_net6addr_insert

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Casey Schaufler <casey@schaufler-ca.com>
Cc: linux-security-module@vger.kernel.org
Cc: Paul Moore <paul@paul-moore.com>
Cc: James Morris <jmorris@namei.org>
Cc: "Serge E. Hallyn" <serge@hallyn.com>