doc: add .md to the link
Checklist
-
make -j4 test
(UNIX), orvcbuild test nosign
(Windows) passes -
tests and/or benchmarks are included -
documentation is changed or added -
commit message follows commit guidelines
Affected core subsystem(s)
Description of change
fix a wrong link to ../topics/the-event-loop-timers-and-nexttick.md