docs: net: bonding: fix typos

The bonding documentation had several "insure" which is not
properly used in the context. Suggest to change to "ensure"
to improve readability.

Signed-off-by: shunlizhou <shunlizhou@aliyun.com>
Link: https://patch.msgid.link/20241216135447.57681-1-shunlizhou@aliyun.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>