Add custom exceptions md #5788

[timm167]

Description

Changes made in content/python/concepts/errors/errors.md.

Adds sub-section in errors.md to provide a description and example usage of Custom Exceptions in Python.

The section includes three subheadings describing the process of first defining, second using, and third the results of custom exceptions.

Issue Solved

Closes #5764

Type of Change

• Editing an existing entry (fixing a typo, bug, issues, etc)

Checklist

• All writings are my own.
• My entry follows the Codecademy Docs style guide.
• My changes generate no new warnings.
• I have performed a self-review of my own writing and code.
• I have checked my entry and corrected any misspellings.
• I have made corresponding changes to the documentation if needed.
• I have confirmed my changes are not being pushed from my forked main branch.
• I have confirmed that I'm pushing from a new branch named after the changes I'm making.
• I have linked any issues that are relevant to this PR in the Issues Solved section.

[timm167]

Apologies for previous errors i had to close the last pull request and re-fork the repo. I hope this works fine now.

[SaviDahegaonkar]

Hey @timm167,
Have you implemented the changes? Please let me know so that I can do the review.

Thanks,
Savi

[timm167]

Hi @SaviDahegaonkar

Apologies I am not certain what changes you mean?

For context I previously submitted a pull request but I had made a mistake submitting it so even though the changes were approved it wasn't possible for me to sign the CLA.

I have signed the CLA if that is what you are asking?

I also implemented all my initial changes to the docs that were previously accepted as well as the tweaks made my the approver.

Or do you mean some other changes that I need to make?

Apologies for my confusion.