Update old link

[PowerChell]

Earth Lab -- Pull Request Template

Welcome to EarthDataScience.org!

Before submitting a Pull Request please be sure to submit an issue that describes what the contents of the PR addresses.

IMPORTANT: Please do not use this repository as a practice activity to learn how to use GitHub! Only submit a PR after:

1. Submitting an issue with a valid item that you wish to address in earthpy
2. Getting approval from one of the maintainers to submit a formal PR.

Description

Change of the base URL has the Earth Data Analytics Professional Graduate Certificate link rerouting to the homepage of Earthlab. I fixed that issue, updated some wording, and updated the Earthlab URL while I was here (even though the link is rerouting to the new page fine).

Fixes #1046

Type of change

Please delete options that are not relevant.

• 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 not work as expected)
• Documentation update

How Has This Been Tested?

Please describe the tests that you ran to verify your changes. Provide instructions so we can reproduce. Please also list any relevant details for your test configuration

• Test A
• Test B

Checklist:

• I have already submitted an issue and i was invited to submit a pr by an earthdatascience.org maintainer
• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules
• I have checked my code and corrected any misspellings

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