Fix the docs and do some cleanup

[elbrujohalcon]

Some functions were unnecessarily exported, some others were undocumented.

[codecov]

Codecov Report

Merging #186 (f026953) into main (0b3c04b) will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##             main     #186   +/-   ##
=======================================
  Coverage   92.82%   92.82%           
=======================================
  Files          10       10           
  Lines         432      432           
=======================================
  Hits          401      401           
  Misses         31       31           

Impacted Files	Coverage Δ
src/wpool_pool.erl	96.37% <ø> (ø)
src/wpool_process_callbacks.erl	90.00% <ø> (ø)
src/wpool_utils.erl	100.00% <ø> (ø)
src/wpool_process.erl	82.35% <100.00%> (+0.64%)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 0b3c04b...f026953. Read the comment docs.

[NelsonVides]

Excellent 👍🏽