Fix docs on how to select using the bls parameter

[bhazelton]

Description

Fix errors in documentation on using the select method with the bls parameter.

Note that there is an existing test, test_param_select_bls in test_simsetup.py, that tests that this works as documented in this PR.

Motivation and Context

fixes #333

Types of changes

• [ ] Bug fix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to change)
• [ ] Reference simulation update or replacement
• [x] Documentation change (documentation changes only)
• [ ] Version change
• [ ] Build or continuous integration change

Checklist:

For all pull requests:

• [x] I have read the contribution guide.
• [x] My code follows the code style of this project.

Documentation change checklist:

• [ ] Any updated docstrings use the numpy docstring format.
• [x] If this is a significant change to the readme or other docs, I have checked that they are rendered properly on ReadTheDocs. (you may need help to get this branch to build on RTD, just ask!)

[codecov[bot]]

Codecov Report

Merging #383 (6c48d92) into main (1f88b96) will not change coverage. The diff coverage is n/a.

@@           Coverage Diff           @@
##             main     #383   +/-   ##
=======================================
  Coverage   99.17%   99.17%           
=======================================
  Files          13       13           
  Lines        2054     2054           
=======================================
  Hits         2037     2037           
  Misses         17       17           

---

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 1f88b96...6c48d92. Read the comment docs.