doc: fix EventEmitter#eventNames() example
Checklist
-
documentation is changed or added -
the commit message follows commit guidelines
Affected core subsystem(s)
doc
Description of change
Replace myErr
with myEE
in one place (that was obviously a mistype).
Fix the expected output to have the actual formatting.
This was overlooked in #5617 (I also didn't notice that).
/cc @jasnell