Add godoc to tools

[AlekSi]

Checklist

• Tests are added for new functionality or fixed bugs.
• task all passes.

See CONTRIBUTING.md for more details.

[codecov]

Codecov Report

Merging #789 (efd10f8) into main (eb26ce0) will decrease coverage by 0.08%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             main     #789      +/-   ##
==========================================
- Coverage   59.32%   59.24%   -0.09%     
==========================================
  Files         212      212              
  Lines        9348     9348              
==========================================
- Hits         5546     5538       -8     
- Misses       3159     3165       +6     
- Partials      643      645       +2     

Impacted Files	Coverage Δ
internal/handlers/pg/msg_dbstats.go	65.11% <0.00%> (-6.98%)	⬇️
internal/clientconn/listener.go	73.86% <0.00%> (-3.41%)	⬇️
internal/wire/msg_header.go	69.04% <0.00%> (-2.39%)	⬇️
internal/wire/msg_body.go	36.50% <0.00%> (-1.59%)	⬇️

Flag	Coverage Δ
FerretDB	62.63% <ø> (-0.32%)	⬇️
MongoDB	7.22% <ø> (ø)
integration	62.74% <ø> (-0.32%)	⬇️
unit	22.99% <ø> (ø)

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