Added a practice section with 2 entries.

[cupOJoseph]

Add a section for challenges and practice coding places. This is separate from tutorials since they aren't simply walk-throughs and require more active learning. After giving several solidity workshops I've had a number of people ask me about building a portfolio and coming up with ideas for practicing and getting better.

It is okay that I added more than 1 entry since it's a new category? I can split it up if that's preferred. Thanks

Checklist

• [x] Each link description starts with an uppercase character and ends with a period.
  Example: solc-js - JavaScript bindings for the Solidity compiler.
• [x] Drop all the A / An prefixes in the descriptions.
• [x] Avoid using the word Solidity in the description.

[bkrem]

Great initiative on this, thanks for your contribution @jschiarizzi 💯

You're absolutely right, a practice/challenge section is needed in the list.

This already looks great; as long as the links are all in good faith (i.e. no phishing links, no excessive self promotion, etc.) and the descriptions are useful you can add as many as you like :)

Will merge now 👍