Improve help on tokens

[lukasmalkmus]

This PR improves the user experience by adding two things:

• An additional help topic on the different token types and how they affect the CLI usage
• An explicit error message when running commands which do not support using an ingest-only token

Overriding the token by flag or environment bypasses the check by assuming a personal token was passed. This is crucial because a deployment can be configured with an ingest token but a personal token can be specified as override.

[codecov]

Codecov Report

Merging #34 (48b23f7) into main (de7d888) will decrease coverage by 0.23%.
The diff coverage is 0.00%.

@@            Coverage Diff             @@
##             main      #34      +/-   ##
==========================================
- Coverage   14.78%   14.54%   -0.24%     
==========================================
  Files           9        9              
  Lines         487      495       +8     
==========================================
  Hits           72       72              
- Misses        400      408       +8     
  Partials       15       15              

Impacted Files	Coverage Δ
cmd/axiom/root/help.go	0.00% <0.00%> (ø)
cmd/axiom/root/help_topic.go	100.00% <ø> (ø)
cmd/axiom/root/root.go	0.00% <0.00%> (ø)
internal/config/config.go	5.71% <0.00%> (-0.17%)	⬇️

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[bahlo]

Love it. Would be even better if there was a command to "upgrade" a token. You could suggest that in the help even