feat: manpages

[caarlos0]

generate and distribute goreleaser's man page using the awesome mango by @muesli 🙏

[codecov]

Codecov Report

Merging #2837 (5898e05) into main (87151f8) will decrease coverage by 0.04%.
The diff coverage is 63.15%.

@@            Coverage Diff             @@
##             main    #2837      +/-   ##
==========================================
- Coverage   84.60%   84.55%   -0.05%     
==========================================
  Files         109      110       +1     
  Lines        8381     8400      +19     
==========================================
+ Hits         7091     7103      +12     
- Misses       1045     1051       +6     
- Partials      245      246       +1     

Impacted Files	Coverage Δ
cmd/man.go	61.11% <61.11%> (ø)
cmd/root.go	100.00% <100.00%> (ø)

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