improvements to documentation and add more tests for BCH code

[Fe-r-oz]

This PR improves the documentation and add more tests for BCH codes by reproducing the table from page 8,9 of the slides.

Edit:

• The code is properly formatted and commented.
• Substantial new functionality is documented within the docs.
• All new functionality is tested.
• All of the automated tests on github pass.
• We recently started enforcing formatting checks. If formatting issues are reported in the new code you have written, please correct them.

[Fe-r-oz]

Please help review this PR, Thank you!