Docs: Clarify UDP recomendation

[mkarlstrand-splunk]

Update the UDP vs TCP docs section to include the full context of the recommendation contained in the blog post.

https://splunk.github.io/splunk-connect-for-syslog/main/architecture/ https://www.rfaircloth.com/2020/05/21/performant-and-reliable-syslog-udp-is-best/

[rjha-splunk]

@nandinivij can you please update this.

[rjha-splunk]

@mateuszpierzchala-splunk Can you please take a look?

[mateuszpierzchala-splunk]

@rjha-splunk sure, np

[mateuszpierzchala-splunk]

closed by #1801