added in Markdown for singledispathc() documentation

[freshcakewtf]

Description

Issue Solved

Closes #7459

Type of Change

• Adding a new entry
• Editing an existing entry (fixing a typo, bug, issues, etc)
• Updating the documentation

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 made corresponding changes to the documentation if needed.
• I have confirmed my changes are not being pushed from my forked main branch.
• I have checked my entry and corrected any misspellings.
• 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.

[CLAassistant]

All committers have signed the CLA.

[freshcakewtf]

Signed CLA and missed the check boxes earlier for my push. I am not pushing from a branch named after the changes i made. I am pushing from a branch named after my GitHub Account.

Also, should I link to Pythons official doc on functools? Some of my writings, Lines 3 and 18, are paraphrased from their documentation https://docs.python.org/3/library/functools.html

[mamtawardhani]

Looks good for a second review! 🚀