docstrings for backend hooks (#994)

Author: rmorshea

src/reactpy/backend/hooks.py

@@ -12,15 +12,18 @@
 
 
 def use_connection() -> Connection[Any]:
+    """Get the current :class:`~reactpy.backend.types.Connection`."""
     conn = use_context(ConnectionContext)
     if conn is None:
         raise RuntimeError("No backend established a connection.")  # pragma: no cover
     return conn
 
 
 def use_scope() -> MutableMapping[str, Any]:
+    """Get the current :class:`~reactpy.backend.types.Connection`'s scope."""
     return use_connection().scope
 
 
 def use_location() -> Location:
+    """Get the current :class:`~reactpy.backend.types.Connection`'s location."""
     return use_connection().location