rn-137: Add learngit.io updates to tools & sites

[JackLot]

Add resource to "Git tools & sites". Minor formatting fix (remove blank newline).

[chriscool]

@JackLot , sorry it looks like we missed this.

@jnareb, could you take a look for the next edition?

[JackLot]

Thanks for noticing Chris. If this could be considered for the next addition, that would be appreciated. Let me know if I can do anything to help.

[jnareb]

LearnGit.io was already mentioned in Git Rev News Edition #108, #127, and #136 (in passing).

[JackLot]

Yes true. LearnGit has been mentioned twice before, I think most recently issue 127. I wanted to specifically let folks know what has been added/changed, and that more of the platform is now open without needing an account.

If you don't feel it's appropriate for the newsletter, feel free to close.

[jnareb]

@JackLot if you could offer a summary of what changed since a year ago, please.

[JackLot]

Sure. Compared to last year when the only thing on LearnGit was video lessons and a few quizzes, this update added:

• UX overhaul (before/after below)
• Type-it-yourself practice exercises (ex)
• Interactive visualizations for core concepts (ex <-- click the "Explore" tab)
• Opened the platform. Before only available to members or students. Probably 75% of locked lesson content is available for free on my YT. LearnGit is a more guided, in-depth thing if people prefer that.

A more in depth explanation: https://learngit.io/posts/learngit-v2-is-here