Add git trick: reflog and checkout tips (#228)

* Enhance git tricks with reflog and checkout tips

* Update 01_version_control/my_favorite_neat_little_git_trick_demo.md

---------

Co-authored-by: Benjamin Uekermann <benjamin.uekermann@gmail.com>
Co-authored-by: Benjamin Uekermann <benjamin.uekermann@ipvs.uni-stuttgart.de>

Author: elshereif

01_version_control/my_favorite_neat_little_git_trick_demo.md

@@ -15,6 +15,8 @@
             pretty = format:%C(auto,yellow)%h %C(auto,blue)%>(12,trunc)%ad %C(auto,green)%<(20,trunc)%aN%C(auto,reset)%s%C(auto,red)% gD% D
     ```
 
+- If you rebased/merged and messed up your history, use `git reflog` to go back to a previous state
+- If you only need one file from another commit or branch, use `git checkout <branch_or_sha> -- <path>`
 - Use [Git LFS](https://git-lfs.com/) for big files >10 MB or for non-diffable binaries (e.g., images, media, archives, shared libraries).
 
 ## Tricks from Winter Term 2024/25