What type of PR is this?

Uncomment only one /kind <> line, hit enter to put that in a new line, and remove leading whitespaces from that line:

/kind task

What does this PR do / why do we need it:

Clarify that the CLI needs to trust the server-side certificate, which caused confusion when trying to deploy a security cluster.

Which issue(s) this PR fixes:

Fixes ##I4A7FA:[1.4.0RC2][on-yarn] hetu-cli fails with untrusted certificate exception when connecting to a secure OLK instance.

Special notes for your reviewers:

It turns out the docs do already mention that the CLI needs to trust the server-side certificate, but the page mentions it very quickly at the end of a paragraph, and it may be easy to miss. The changes here are meant to try to make it more clear to the reader.