Clarify terminology: SmartProxy/SmartProxyServer, Internal/External/Isolated

[asteflova]

          I am unsure about "isolated" here. Maybe reword to "than an {SmartProxyServer}" instead?

IMHO we should drop "internal", "external", and possibly "isolated" and instead use "SmartProxy" and "SmartProxyServer" as attributes.

Originally posted by @maximiliankolb in #2607 (comment)

[asteflova]

Re: isolated/external/internal:

• We shouldn't use "isolated capsule" or "isolated host": "Capsule/CapsuleServer" or "host" is enough.
• Specifically for files guides/common/modules/con_smartproxy-networking.adoc, occurrences of "isolated" still persist in the diagrams, so these need to be updated.

Re: SmartProxy/SmartProxyServer: We need to clarify these terms and when to use them. @maximiliankolb @Lennonka

[maximiliankolb]

Strongly disagree to use "host" when you prefer to Foreman/Katello/Satellite/orcharhino infrastructure.

Otherwise, full ACK. I will post my table/explanations here ASAP.

[maximiliankolb]

Closed #2867

Reword "internal Smart Proxy" and "external Smart Proxy" #2867

• fix glossary
• architecture guide: explain difference between Smart Proxy and Smart Proxy Server
• possibly: fix images