[web] Added some links to git guis.

web/content/docs/devguide/troubleshooting/git/index.md

@@ -14,3 +14,16 @@ weight = 1070
 If you have any Git-related questions first look at these links:
 
 - [Git Flight Rules](https://github.com/k88hudson/git-flight-rules)
+- [Git Book](https://git-scm.com/book/en/v2)
+
+## Graphical User Interfaces for Git
+
+Although we recommend to learn Git via its command line interface a graphical interface may help in using Git. There are [numerous tools available](https://git-scm.com/downloads/guis/).
+
+The following tools are used by OGS developers:
+
+- [`git-gui`](https://git-scm.com/docs/git-gui) and [`gitk`](https://git-scm.com/docs/gitk), Linux / Mac / Windows, free, often pre-installed with git
+- [SourceTree](https://www.sourcetreeapp.com/), Mac / Windows, free
+- [Fork](https://git-fork.com/), Mac / Windows, commercial with free evaluation, supports our [branching / rebasing workflow](https://github.com/fork-dev/TrackerWin/issues/1432)
+- [`tig`](https://jonas.github.io/tig/), Linux / Mac / Windows, command line repository browser
+- Some VS Code extensions like [Git Graph](https://marketplace.visualstudio.com/items?itemName=mhutchie.git-graph)