Improve instructions on Proxy page

[paulirwin]

This PR proposes changes to the instructions on the members' Proxy page, to help clarify some language and add answers to some questions on the mailing list. This language was improved with the use of ChatGPT.

I am merely proposing changes here; I am very open to feedback or changes to the language or formatting. I also would like this to be reviewed to ensure it is correct (particularly around the "Submit" sentence).

I would recommend, of course, not merging this PR until after the upcoming members meeting, to avoid confusion. Please let me know if I need to run this language by anyone else, too.

This has been tested locally using Docker. Here is a screenshot of the rendered HTML:

[noelportillo]

Ok