doc(opts): clarify --no_advertise

[JensRantil]

This commit came out of [1] and [2]. Clarifies current behaviour much
better.

[1] #950 (comment)
[2] #952

• Link to issue, e.g. Resolves #NNN
• Documentation added (if applicable)
• Tests added
• Branch rebased on top of current master (git pull --rebase origin master)
• Changes squashed to a single commit (described here)
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• You have certified that the contribution is your original work and that you license the work to the project under the Apache 2 license

/cc @nats-io/core

[kozlovic]

The no_advertise is really for a server to not advertise its client host:port to the clients. That is, if a server is configured with no_advertise, it won't send to clients connecting to it information regarding other servers client host:port in the cluster (but also not communicate its to its members).
So yes, technically a server's own client host:port info is not sent to the members of the clusters, but really the key point is that it is not sending info to its clients.
Is that how you understood it and still think that the addition of cluster members is important?

[wallyqs]

@JensRantil apologies that may have contributed to the confusion 😕, when setting no_advertise cluster members are still advertised to other cluster peers so we can actually close this issue since change not needed (updated related issue as well #952 (comment))

[wallyqs]

Closing since no_advertise does advertise to cluster members and can be used to disable advertising to clients only.