update URLs to R and Julia templates

[acocac]

Before review

• Work in progress
• Ready for review
• Need help!

Description

Update links to R and Julia Notebook Repository Templates.

Motivation and Context

Missing links to R and Julia Notebook Repository Templates.

How has this been tested?

Locally in MacOS.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• New notebook and/or content
• Documentation notebook/content update
• Other (please describe):
• Feature change (upgrade version)

Checklist:

• My code follows the code style of this project: Python
• I have read the CONTRIBUTING doc
• 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
• I have added tests to cover my changes
• I have tested the changes and verified that they work and don't break anything (as well as I can manage)

Additional information

Related to #126

[netlify]

✅ Deploy Preview for the-environmental-ds-book canceled.

Name	Link
🔨 Latest commit	c8e51b4
🔍 Latest deploy log	https://app.netlify.com/sites/the-environmental-ds-book/deploys/6408b8a32bdbb00008296d01