Add docs for get_app_dir()

docs/src/app_dir/tutorial001.py

@@ -0,0 +1,16 @@
+from pathlib import Path
+
+import typer
+
+APP_NAME = "my-super-cli-app"
+
+
+def main():
+    app_dir = typer.get_app_dir(APP_NAME)
+    config_path = Path(app_dir) / "config.json"
+    if not config_path.is_file():
+        typer.echo("Config file doesn't exist yet")
+
+
+if __name__ == "__main__":
+    typer.run(main)

docs/tutorial/app-dir.md

@@ -0,0 +1,35 @@
+You can get the application directory where you can, for example, save configuration files with `typer.get_app_dir()`:
+
+```Python hl_lines="9"
+{!./src/app_dir/tutorial001.py!}
+```
+
+It will give you a directory for storing configurations appropriate for your CLI program for the current user in each operating system.
+
+Check it:
+
+<div class="termy">
+
+```console
+$ python main.py
+
+Config file doesn't exist yet
+```
+
+</div>
+
+## About `Path`
+
+If you hadn't seen something like that:
+
+```Python
+Path(app_dir) / "config.json"
+```
+
+A `Path` object can be used with `/` and it will convert it to the separator for the current system (`/` for Unix systems and `\` for Windows).
+
+If the first element is a `Path` object the next ones (after the `/`) can be `str`.
+
+And it will create a new `Path` object from that.
+
+If you want a quick guide on using `Path()` you can check <a href="https://realpython.com/python-pathlib/" target="_blank">this post on Real Python</a> or <a href="https://treyhunner.com/2018/12/why-you-should-be-using-pathlib/" target="_blank">this post by Trey Hunner</a>.

mkdocs.yml

@@ -49,6 +49,7 @@ nav:
             - File: 'tutorial/parameter-types/file.md'
         - Ask with Prompt: 'tutorial/prompt.md'
         - Progress Bar: 'tutorial/progressbar.md'
+        - CLI Application Directory: 'tutorial/app-dir.md'
     - Alternatives, Inspiration and Comparisons: 'alternatives.md'
     - Help Typer - Get Help: 'help-typer.md'
     - Development - Contributing: 'contributing.md'