doc: fix out of date sections in n-api doc
Fixes: https://github.com/nodejs/node/issues/13469 Fixes: https://github.com/nodejs/node/issues/13458
Checklist
-
make -j4 test
(UNIX), orvcbuild test
(Windows) passes -
documentation is changed or added -
commit message follows [commit guidelines]
Affected core subsystem(s)
doc, n-api