updating the presentations and fixing link for Rstudio sessio. Rstudio session is not rendering in Liascript yet, so link is directed to github MD reading format

Author: bpiereck

presentation/day1-intro-git-github.html renamed to presentation/intro_git_day1.html

@@ -42,4 +42,4 @@
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 11. GitHub & Rstudio [🔗](https://liascript.github.io/course/?https://github.com/vibbits/introduction-github/blob/master/tutorials/11_github_rstudio/tutorial.md)
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-[<img src="https://raw.githubusercontent.com/vibbits/introduction-github/master/images/images_tutorial/rstudio-1.PNG" width="200"/>](https://liascript.github.io/course/?https://github.com/vibbits/introduction-github/blob/master/tutorials/11_github_rstudio/tutorial.md)
+[<img src="https://raw.githubusercontent.com/vibbits/introduction-github/master/images/images_tutorial/rstudio-1.PNG" width="200"/>](https://github.com/vibbits/introduction-github/blob/master/tutorials/11_github_rstudio/tutorial.md)