docs: add instructions for gnofaucet

[iuricmp]

This PR adds a small instruction to allow users run GnoFaucet connected with local gnokey.

refs: leohhhn/gnoland_zero_to_hero#1

Contributors' checklist...

• Added new tests, or not needed, or not feasible
• Provided an example (e.g. screenshot) to aid review or the PR is self-explanatory
• Updated the official documentation or not needed
• No breaking changes were made, or a BREAKING CHANGE: xxx message was included in the description
• Added references to related issues and PRs
• Provided any useful hints for running manual tests
• Added new benchmarks to generated graphs, if any. More info here.

[leohhhn]

Hey @iuricmp, thanks for pointing this out, you were a bit ahead of me on documenting this :)

While I think it is super useful to document common errors, I think doing it this way is a little bit cluttering - this would not be scalable if we keep on adding common errors.

How I would go about documenting this:

1. accurately define the usages of gnokey and gnofaucet, ie, document the --home argument in both (afaik it's missing in the options list),
2. mention in this file that gnofaucet relies on the gnokey home dir to look for keys (similar to what you did, just not under ::danger::, but as normal text)
3. further down the line, have a common errors/issues/faq page for docs, which would be an organized place to dump these things.

Down the line, the plan is to have documentation for tools be auto-exported from the --help option of the tool, allowing for in-sync tool and docs development.

I suggest you do 1. & 2., and we can discuss 3 :)

Thanks!

[iuricmp]

I'm closing this PR since it seems that this version of gnofaucet will be discontinued in favor of https://github.com/gnolang/faucet.