Doc correction: ngx.* log level constants context missing init_by_lua, init_worker_by_lua

[kailiu42]

I noticed that the doc does not mention log level constatns ngx.INFO/ERR/ALERT etc. are available in phases such as init_by_lua, init_worker_by_lua. But they are actually available in these phases. Could you correct the doc?

[detailyang]

Thanks for you reply, I try to create a PR to fix:)

[agentzh]

#908 is already merged. Consider it resolved.