test,doc: fix https agent minVersion/maxVersion test and docs
test: fix test-https-agent-additional-options.js
`value` was always being assigned to an `undefined` property of an
Array. Thus, the assertions that depended on `value` being defined were
never being checked. Assign `value` the correct...er...value.
test add tests for missing https agent options
Add test that minVersion and maxVersion options are accepted. This
should complete coverage for lib/https.js.
Refs: https://codecov.io/gh/nodejs/node/src/ec0dcd720e10831b3e783b415c5dc011ed5be2f8/lib/https.js
doc: revise TLS minVersion/maxVersion text
Minor changes mostly to improve compliance with our style guide.