Add hands-on structrure

Author: woojiahao

docs/architecture/hands-on-structure.md

@@ -3,3 +3,51 @@ title: Hands-on Structure
 parent: Architecture
 nav_order: 1
 ---
+
+All hands-ons are stored within the `hands_on` folder of the [`exercises`](https://github.com/git-mastery/exercises).
+
+They are represented by a single Python file, whose name is the hands-on ID (replacing `_` with `-`).
+
+Hands-ons are not graded and the progress is not tracked. They are only present to help setup the student's folder structure for a given lesson!
+
+{: .note }
+
+Git-Mastery users will prefix `hp-` before the hands-on names, but internally, we do not use this prefix as the `hands_on` folder is sufficient for us.
+
+## File structure
+
+Since the hands-on is only comprised of a single file, there isn't a lot of complexity to it.
+
+```python
+import subprocess
+from sys import exit
+from typing import List, Optional
+
+__requires_git__ = True
+__requires_github__ = True
+
+
+def run_command(command: List[str], verbose: bool) -> Optional[str]:
+    try:
+        result = subprocess.run(
+            command,
+            capture_output=True,
+            text=True,
+            check=True,
+        )
+        if verbose:
+            print(result.stdout)
+        return result.stdout
+    except subprocess.CalledProcessError as e:
+        if verbose:
+            print(e.stderr)
+        exit(1)
+
+
+def download(verbose: bool):
+    pass
+```
+
+The setup instructions of the hands-on go under `download`.
+
+`__requires_git__` and `__requires_github__` tells the Git-Mastery app whether to run automatic verification that the student has already setup Git and/or Github CLI correctly!