doc: excise "periodically" before "emit events"

"periodically" implies regular time intervals between emitted events,
but as first example, "peer connects", implies, the time intervals
may be irregular or unpredictable.

PR-URL: #20581
Reviewed-By: Anna Henningsen <[email protected]>
Reviewed-By: Vse Mozhet Byt <[email protected]>

Author: jeswcollins

doc/api/events.md

@@ -8,8 +8,7 @@
 
 Much of the Node.js core API is built around an idiomatic asynchronous
 event-driven architecture in which certain kinds of objects (called "emitters")
-periodically emit named events that cause `Function` objects ("listeners") to be
-called.
+emit named events that cause `Function` objects ("listeners") to be called.
 
 For instance: a [`net.Server`][] object emits an event each time a peer
 connects to it; a [`fs.ReadStream`][] emits an event when the file is opened;