[Concept Entry] MySQL COVAR_POP() function

[codecademy-docs]

Reason/inspiration (optional)

We would like a new entry on the COVAR_POP concept in MySQL. The entry should go in a new file under docs/content/mysql/concepts/build-in-functions/terms/covarPop/covarPop.md. 
 
The entry should include:

• An introduction to the concept

• A Syntax section that provides the syntax for the concept (if applicable)

• An Example section that provides an example demonstrating the concept in use (if applicable)

Please refer to the concept entry template, content standards, and markdown style guide when working on the PR for this issue.

Entry Type (select all that apply)

New Concept Entrty for Existing Topic

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[MrShade138]

I would like to considered for assignment for this issue. This is my first issue. I was directed here through the GitHub course and I am familiar with SQL so this seems like something I can work on.

[SaviDahegaonkar]

Hey @MrShade138 ,
You’re assigned 🎉 In addition to the documents linked in the description, please also look at the Contribution Guide. After creating a PR, the maintainer(s) (with the collaborator label) will add comments/suggestions to address any revisions before approval.

Thanks & Regards,
Savi