Document removal of fakemodule

docs/source/whatsnew/pr/incompat-drop-fakemodule.rst

@@ -0,0 +1,1 b''
+* The module ``IPython.core.fakemodule`` has been removed.

docs/autogen_api.py

@@ -35,7 +35,7 b" if __name__ == '__main__':"
                                         r'\.zmq',
                                         ]
 
-    docwriter.module_skip_patterns += [ r'\.core\.fakemodule',
+    docwriter.module_skip_patterns += [
                                         r'\.testing\.iptest',
                                         # Keeping these disabled is OK
                                         r'\.parallel\.controller\.mongodb',