small typo

[Bannirui]

Describe the problem this feature solves

Locating at src/event/modules/ngx_kqueue_module.c#L86, as below

        NULL,                              /* add an connection */
        NULL,                              /* delete an connection */

a small typo — it should be 'a connection'

[ac000]

I think we're unlikely to fix such things for the sake of it. Too much churn for no real gain...