add slides for upcoming git training

2021/2021-03-18_basicGitTraining/slides/best_practices.md

@@ -2,9 +2,9 @@
 
 * `pull` before `push`
 * Work on your <font color="red">own</font> branch (in your own fork), and **not** on `master` and **not** on `develop`
-* Do **not push** to `master`, but **submit a Merge Request (MR)**
-* Get your code **reviewed** by your peers (submit a MR!)
-* Submit a MR **often**!
+* Do **not push** to `master`, but **submit a Pull Request (PR)**
+* Get your code **reviewed** by your peers (submit a PR!)
+* Submit a PR **often**!
 * `clone` a repository, do not download the `.zip` file.
 * Do **not** combine `git` commands
    ```bash