feat: enabled loading http-api-token from file

[piksel]

This adds http-api-token to the list of arguments that watchtower tries to load from a file if they exist (fixes #1711).

Additionally, this adds some more (easier to find) docs about the usage (fixes #1390).

[codecov]

Codecov Report

Patch coverage: 100.00% and project coverage change: +0.01% 🎉

Comparison is base (139f672) 67.59% compared to head (58e9cd2) 67.60%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1728      +/-   ##
==========================================
+ Coverage   67.59%   67.60%   +0.01%     
==========================================
  Files          26       26              
  Lines        2379     2380       +1     
==========================================
+ Hits         1608     1609       +1     
  Misses        672      672              
  Partials       99       99              

Files Changed	Coverage Δ
internal/flags/flags.go	85.20% <100.00%> (+0.02%)	⬆️

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[lonix1]

This is a great update. I'm going to try it right away. Thank you!

[lonix1]

Ok I see the new docker image isn't released yet. Are you planning to release it soon?

[piksel]

You can try it using containrrr/watchtower:latest-dev, but the plan is to do a new release within a week.