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

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

[codecov]

Codecov Report

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

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

❗ 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

@@            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	Coverage Δ
aquadoggo/src/network/behaviour.rs	44.95% <50.00%> (+0.91%)	⬆️
aquadoggo/src/config.rs	80.00% <100.00%> (ø)
aquadoggo/src/network/config.rs	100.00% <100.00%> (ø)

... and 1 file with indirect coverage changes

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