Mention the path argument in the documentation

Signed-off-by: Filipe Laíns <lains@riseup.net>

Author: FFY00

Doc/library/importlib.rst

@@ -987,11 +987,14 @@ find and load modules.
 
 .. class:: NamespacePath(name, path, path_finder)
 
-   Represents a namespace package's path.  It uses the module *name* to find its
-   parent module, and from there it looks up the parent's
-   :attr:`module.__path__`.  When this changes, the module's own path is
-   recomputed, using *path_finder*. For top-level modules, the parent module's
-   path is :data:`sys.path`.
+   Represents a namespace package's path.
+
+   It uses the module *name* to find its parent module, and from there it looks
+   up the parent's :attr:`module.__path__`.  When this changes, the module's own
+   path is recomputed, using *path_finder*. The initial package path value is
+   set to *path*.
+
+   For top-level modules, the parent module's path is :data:`sys.path`.
 
 
 .. class:: SourceFileLoader(fullname, path)

Lib/importlib/_bootstrap_external.py

@@ -1080,11 +1080,14 @@ def get_filename(self, fullname):
 
 
 class NamespacePath:
-    """Represents a namespace package's path.  It uses the module name
-    to find its parent module, and from there it looks up the parent's
-    __path__.  When this changes, the module's own path is recomputed,
-    using path_finder.  For top-level modules, the parent module's path
-    is sys.path."""
+    """Represents a namespace package's path.
+
+    It uses the module name to find its parent module, and from there it looks
+    up the parent's __path__. When this changes, the module's own path is
+    recomputed, using path_finder. The initial package path value is set to path.
+
+    For top-level modules, the parent module's path is sys.path.
+    """
 
     # When invalidate_caches() is called, this epoch is incremented
     # https://bugs.python.org/issue45703