added a section on branches to git.md

git.md

@@ -2,10 +2,29 @@
 
 ## Table of contents
 
-- [git submodule](#git-submodule)
+- [branches](#branches)
+  - [create a branch](#create-a-branch)
+- [submodules](#submodules)
 
 
-## git submodule
+## branches
+
+### create a branch
+
+To create a branch use subcommand `branch` or `checkout` with flag `-b`:
+```bash
+# create new branch ('base-branch' is optional)
+git branch <branch-name> <base-branch>
+git checkout -b <branch-name> <base-branch>
+
+# switch branch ('checkout -b' combines the 'branch' and 'switch' subcommands)
+git switch <branch-name>
+```
+
+
+## submodules
+
+To fetch submodules of a cloned repository use:
 ```bash
 # do it manually
 git submodule init