chore: improve documentation for loading plugins from setuptools entr…

…y_points

simplug.py

@@ -791,7 +791,14 @@ def load_entrypoints(
         group: str | None = None,
         only: str | Iterable[str] = (),
     ) -> None:
-        """Load plugins from setuptools entry_points"""
+        """Load plugins from setuptools entry_points
+
+        Args:
+            group: The group of the entry_points
+            only: The names of the entry_points to load. If it's a str, it
+                means only load this entry_point. If it's a list of str, it
+                means load all the entry_points in the list.
+        """
         group = group or self.project
 
         if isinstance(only, str):

tests/test_simplug.py

@@ -1133,7 +1133,7 @@ def hook(arg):
         f"{sys.executable} {plugin_dir}/setup.py "
         f"install --install-lib {install_dir} 1>/dev/null 2>/dev/null"
     )
-    simplug.load_entrypoints(only="None")
+    simplug.load_entrypoints(only="None")  # Nothing loaded
     assert simplug.hooks.hook(1) == [1]
 
     simplug.load_entrypoints()