Correct broken links in gitkraken-tutorial.md

correct broken links:
* share link in web app
* additional material link

Author: ngammarano

gui-tool-tutorials/gitkraken-tutorial.md

@@ -111,12 +111,12 @@ Soon I'll be merging all your changes into the master branch of this project. Yo
 
 Congrats!  You have just completed the standard _fork -> clone -> edit -> PR_ workflow that you'll encounter often as a contributor!
 
-Celebrate your contribution and share it with your friends and followers by going to [web app](https://firstcontributions.github.io/first-contributions/#social-share).
+Celebrate your contribution and share it with your friends and followers by going to [web app](https://firstcontributions.github.io/#social-share).
 
 You could join our slack team in case you need any help or have any questions. [Join slack team](https://join.slack.com/t/firstcontributors/shared_invite/enQtMzE1MTYwNzI3ODQ0LTZiMDA2OGI2NTYyNjM1MTFiNTc4YTRhZTg4OWZjMzA0ZWZmY2UxYzVkMzI1ZmVmOWI4ODdkZWQwNTM2NDVmNjY).
 
 
-### [Additional material](../additional-material/git_workflow_senarios/additional-material.md)
+### [Additional material](../additional-material/git_workflow_scenarios/additional-material.md)
 
 
 ## Tutorials Using Other Tools