Improves the PanelFrontend docs (#14493)

Co-authored-by: Marc Skov Madsen <[email protected]>
Co-authored-by: thomas chaton <[email protected]>
Co-authored-by: Adrian Wälchli <[email protected]>
Co-authored-by: Felonious-Spellfire <[email protected]>
Co-authored-by: Jirka Borovec <[email protected]>
Co-authored-by: Mansy <[email protected]>
(cherry picked from commit 10a4b24)

src/lightning_app/frontend/panel/app_state_watcher.py

@@ -1,9 +1,9 @@
-"""The AppStateWatcher enables a Frontend to.
+"""The ``AppStateWatcher`` enables a Frontend to:
 
 - subscribe to App state changes
 - to access and change the App state.
 
-This is particularly useful for the PanelFrontend but can be used by other Frontends too.
+This is particularly useful for the ``PanelFrontend`` but can be used by other frontends too.
 """
 from __future__ import annotations
 
@@ -26,15 +26,16 @@
 
 
 class AppStateWatcher(Parameterized):
-    """The AppStateWatcher enables a Frontend to:
+    """The `AppStateWatcher` enables a Frontend to:
 
     - Subscribe to any App state changes.
     - To access and change the App state from the UI.
 
-    This is particularly useful for the PanelFrontend, but can be used by
-    other Frontend's too.
+    This is particularly useful for the `PanelFrontend , but can be used by
+    other frontends too.
 
-    Example:
+    Example
+    -------
 
     .. code-block:: python
 
@@ -54,10 +55,10 @@ def update(state):
 
     This would print ``The counter was updated to 2``.
 
-    The AppStateWatcher is built on top of Param which is a framework like dataclass, attrs and
+    The ``AppStateWatcher`` is built on top of Param, which is a framework like dataclass, attrs and
     Pydantic which additionally provides powerful and unique features for building reactive apps.
 
-    Please note the AppStateWatcher is a singleton, i.e. only one instance is instantiated
+    Please note the ``AppStateWatcher`` is a singleton, i.e., only one instance is instantiated
     """
 
     state: AppState = ClassSelector(
@@ -75,7 +76,7 @@ def __new__(cls):
 
     @requires("param")
     def __init__(self):
-        # It's critical to initialize only once
+        # It is critical to initialize only once
         # See https://github.com/holoviz/param/issues/643
         if not hasattr(self, "_initialized"):
             super().__init__(name="singleton")

src/lightning_app/frontend/panel/panel_frontend.py

@@ -27,25 +27,36 @@ def _has_panel_autoreload() -> bool:
 
 
 class PanelFrontend(Frontend):
-    """The PanelFrontend enables you to serve Panel code as a Frontend for your LightningFlow.
+    """The `PanelFrontend` enables you to serve Panel code as a Frontend for your LightningFlow.
 
-    To use this frontend, you must first install the `panel` package:
+    Reference: https://lightning.ai/lightning-docs/workflows/add_web_ui/panel/
+
+    Args:
+        entry_point: The path to a .py or .ipynb file, or a pure function. The file or function must contain your Panel
+            code. The function can optionally accept an ``AppStateWatcher`` argument.
+
+    Raises:
+        TypeError: Raised if the ``entry_point`` provided is a class method
+
+    Example:
+
+    To use the `PanelFrontend`, you must first install the `panel` package:
 
     .. code-block:: bash
 
         pip install panel
 
-    Example:
+    Create the files `panel_app_basic.py` and `app_basic.py` with the content below.
 
-    `panel_app_basic.py`
+    **panel_app_basic.py**
 
     .. code-block:: python
 
         import panel as pn
 
         pn.panel("Hello **Panel ⚡** World").servable()
 
-    `app_basic.py`
+    **app_basic.py**
 
     .. code-block:: python
 
@@ -69,20 +80,15 @@ def configure_layout(self):
 
         app = L.LightningApp(LitApp())
 
-    You can start the Lightning server with Panel autoreload by setting the `PANEL_AUTORELOAD`
-    environment variable to 'yes': `PANEL_AUTORELOAD=yes lightning run app app_basic.py`.
+    Start the Lightning server with `lightning run app app_basic.py`.
 
-    Args:
-        entry_point: A pure function or the path to a .py or .ipynb file.
-        The function must be a pure function that contains your Panel code.
-        The function can optionally accept an `AppStateWatcher` argument.
-
-    Raises:
-        TypeError: Raised if the entry_point is a class method
+    For development you can get Panel autoreload by setting the ``PANEL_AUTORELOAD``
+    environment variable to 'yes', i.e. run
+    ``PANEL_AUTORELOAD=yes lightning run app app_basic.py``
     """
 
     @requires("panel")
-    def __init__(self, entry_point: Callable | str):
+    def __init__(self, entry_point: str | Callable):
         super().__init__()
 
         if inspect.ismethod(entry_point):