[docs] Add a procedure on how to stop (cancel) the compaction

[mocchira]

As reported on #1156 (comment), there are some users who can't find any information on how to stop/cancel the compaction because what compaction operations we provide through leofs-adm are

• compact start
• compact suspend
• compact resume
• compact status

so there is no stop/cancel commands.

Unfortunately actually we haven't implemented stop/cancel compaction commands on leofs-adm however there is a workaround to stop/cancel compaction.

As I answered at #1156 (comment), restarting LeoStorage will result in stopping the compaction. we have to document about it on our official document.