Add 'Hands-On Programming with R' to the list

[DDH2004]

What does this PR do?

Add resource(s) | Remove resource(s) | Add info | Improve repo

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Description

Added the Hands-On Programming with R textbook.

Why is this valuable (or not)?

How do we know it's really free?

Author of the book is hosting it on github and says he will keep it free.

For book lists, is it a book? For course lists, is it a course? etc.

It is a book

Checklist:

• Search for duplicates.
• Include author(s) and platform where appropriate.
• Put lists in alphabetical order, correct spacing.
• Add needed indications (PDF, access notes, under construction).
• Used an informative name for this pull request.

Follow-up

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[eshellman]

Nice addition!