[request] Use AGENIX_RULES instead of RULES (and maybe rename secrets.nix too)

[giorgiga]

The names RULES and secrets.nix are very generic and unrelated to agenix, to the point that any conscientious programmer can't avoid adding comments like "this variable holds the path to the agenix rules file" or "this is the agenix rules file" (ok, maybe only OCD programmers are affected).

Could you switch to something like AGENIX_RULES and agenix-rules.nix in a future version? (maintaining backwards-compatibility, of course).

[giorgiga]

BTW: I don't have much experience with either go or nix, but this seems easy enough that I can do it if you are willing to accept a PR (and would rather not do it yourself, of course)

[giorgiga]

BTW (since I'm here I'm not opening a separate issue), a second environment variable for holding what ssh key to use (as per the -i option) would be great... since my id_ed25519 is passphrase-protected I generated a key for agenix, but now I have to specify -i ~/.ssh/agenix_ed25519 every time

[ryantm]

Yeah, I think I'd accept such a PR if it had a suitable migration plan and documentation.

[giorgiga]

That's great - I should be able to work on it this weekend.