Doc: Add list(dict) in stdtypes library (GH-16209)

diff --git a/Doc/library/stdtypes.rst b/Doc/library/stdtypes.rst
index a21c553..3895a97 100644
--- a/Doc/library/stdtypes.rst
+++ b/Doc/library/stdtypes.rst
@@ -4234,6 +4234,10 @@
    These are the operations that dictionaries support (and therefore, custom
    mapping types should support too):
 
+   .. describe:: list(d)
+
+      Return a list of all the keys used in the dictionary *d*.
+
    .. describe:: len(d)
 
       Return the number of items in the dictionary *d*.