Fix incorrect ParallelDirSelector documentation

[revolter]

No description provided.

[codecov]

Codecov Report

Merging #848 (8dc4972) into master (93623fa) will not change coverage.
The diff coverage is n/a.

❗ Current head 8dc4972 differs from pull request most recent head c0efdc0. Consider uploading reports for the commit c0efdc0 to get more accurate results

@@           Coverage Diff           @@
##           master     #848   +/-   ##
=======================================
  Coverage   95.89%   95.89%           
=======================================
  Files          32       32           
  Lines        7594     7594           
  Branches      806      806           
=======================================
  Hits         7282     7282           
  Misses        184      184           
  Partials      128      128           

Impacted Files	Coverage Δ
cadquery/selectors.py	98.14% <ø> (ø)

---

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 93623fa...c0efdc0. Read the comment docs.

[jmwright]

Thanks again @revolter

This is straight-forward, so I'm going to go ahead and merge this one once I figure out why the Windows/Python 3.7 check is failing.

[revolter]

I'm pretty sure it's not related to my changes, but I couldn't restart the job myself.

[jmwright]

@revolter There are weird glitches with builds in the CI system sometimes. It looks like it passed this time. Thanks for the contribution.