[DOC] Expand more on HTTP/TCP proxy in LS to LS communication

[lucabelluccini]

Tell us about the issue

The page https://www.elastic.co/guide/en/logstash/8.11/ls-to-ls.html mentions HTTP Proxy and TCP Proxy, but we need to expand a little bit in order to not create confusion.

What we should add

• For Lumberjack, there is no native support for TCP proxy, so the user would be required to put in place a TCP Proxy somewhere and send data to it and the TCP proxy should be configured to reroute the data properly to the destination host
• For HTTP Output, we have a native proxy parameter https://www.elastic.co/guide/en/logstash/current/plugins-outputs-http.html#plugins-outputs-http-proxy
• For Logstash to Logstash, there is no native support for a proxy (HTTP) in the parameters. Using the JVM http.proxyHost flags is not officially supported nor tested - it might work but it is subject to change

[nandiniverma08]

@lucabelluccini Can I work on this issue ?

[lucabelluccini]

Hello @nandiniverma08 I think you can. If you're going to submit a PR, please ensure to request a review by @karenzone