rate_limit: Remove inaccurate comment in rate_limit decorator.
rate_limit: Remove inaccurate comment in rate_limit decorator.

The data is now stored in memory if things are happening inside tornado.
That aside, there is no reason for a comment on a rate_limit_user call
to talk about low level implementation details of that function.

kou/zulip,hackerkid/zulip,zulip/zulip,rht/zulip,kou/zulip,eeshangarg/zulip,zulip/zulip,zulip/zulip,showell/zulip,hackerkid/zulip,rht/zulip,hackerkid/zulip,punchagan/zulip,kou/zulip,eeshangarg/zulip,rht/zulip,hackerkid/zulip,eeshangarg/zulip,punchagan/zulip,eeshangarg/zulip,kou/zulip,andersk/zulip,andersk/zulip,punchagan/zulip,kou/zulip,eeshangarg/zulip,hackerkid/zulip,andersk/zulip,zulip/zulip,andersk/zulip,andersk/zulip,showell/zulip,eeshangarg/zulip,showell/zulip,showell/zulip,hackerkid/zulip,rht/zulip,rht/zulip,rht/zulip,punchagan/zulip,punchagan/zulip,andersk/zulip,zulip/zulip,zulip/zulip,punchagan/zulip,kou/zulip,showell/zulip,punchagan/zulip,eeshangarg/zulip,andersk/zulip,showell/zulip,kou/zulip,zulip/zulip,hackerkid/zulip,showell/zulip,rht/zulip