Improve consistency and documentation of configuration API

[adzialocha]

• Check consistency (code & text) across all places where we have configurations
• Remove wildcards for block list config
• Fix value_name in clap setup
• Improve documentation
• Do not connect to other relays when relay mode is enabled + give a warning
• Show private key configuration on startup

📋 Checklist

• [x] Add tests that cover your changes
• [x] Add this PR to the Unreleased section in CHANGELOG.md
• [x] Link this PR to any issues it closes
• [x] New files contain a SPDX license header

[codecov[bot]]

Codecov Report

Patch coverage: 75.00% and project coverage change: +0.01% :tada:

Comparison is base (99ed7e8) 92.21% compared to head (8479ae9) 92.23%.

:exclamation: Current head 8479ae9 differs from pull request most recent head a6753c9. Consider uploading reports for the commit a6753c9 to get more accurate results

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #528 +/- ## ========================================== + Coverage 92.21% 92.23% +0.01% ========================================== Files 102 102 Lines 16103 16103 ========================================== + Hits 14849 14852 +3 + Misses 1254 1251 -3 ``` | [Files Changed](https://app.codecov.io/gh/p2panda/aquadoggo/pull/528?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=p2panda) | Coverage Δ | | |---|---|---| | [aquadoggo/src/network/behaviour.rs](https://app.codecov.io/gh/p2panda/aquadoggo/pull/528?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=p2panda#diff-YXF1YWRvZ2dvL3NyYy9uZXR3b3JrL2JlaGF2aW91ci5ycw==) | `44.95% <50.00%> (+0.91%)` | :arrow_up: | | [aquadoggo/src/config.rs](https://app.codecov.io/gh/p2panda/aquadoggo/pull/528?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=p2panda#diff-YXF1YWRvZ2dvL3NyYy9jb25maWcucnM=) | `80.00% <100.00%> (ø)` | | | [aquadoggo/src/network/config.rs](https://app.codecov.io/gh/p2panda/aquadoggo/pull/528?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=p2panda#diff-YXF1YWRvZ2dvL3NyYy9uZXR3b3JrL2NvbmZpZy5ycw==) | `100.00% <100.00%> (ø)` | | ... and [1 file with indirect coverage changes](https://app.codecov.io/gh/p2panda/aquadoggo/pull/528/indirect-changes?src=pr&el=tree-more&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=p2panda)

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