Add missing VM forks in API docs

Author: cburgdorf

docs/api/vm/api.vm.forks.rst

@@ -110,3 +110,69 @@ ByzantiumComputation
 
 .. autoclass:: eth.vm.forks.byzantium.computation.ByzantiumComputation
   :members:
+
+
+Constantinople
+--------------
+
+ConstantinopleVM
+~~~~~~~~~~~~~~~~
+
+.. autoclass:: eth.vm.forks.constantinople.ConstantinopleVM
+  :members:
+
+ConstantinopleState
+~~~~~~~~~~~~~~~~~~~
+
+.. autoclass:: eth.vm.forks.constantinople.state.ConstantinopleState
+  :members:
+
+ConstantinopleComputation
+~~~~~~~~~~~~~~~~~~~~~~~~~
+
+.. autoclass:: eth.vm.forks.constantinople.computation.ConstantinopleComputation
+  :members:
+
+
+Petersburg
+----------
+
+PetersburgVM
+~~~~~~~~~~~~
+
+.. autoclass:: eth.vm.forks.petersburg.PetersburgVM
+  :members:
+
+PetersburgState
+~~~~~~~~~~~~~~~
+
+.. autoclass:: eth.vm.forks.petersburg.state.PetersburgState
+  :members:
+
+PetersburgComputation
+~~~~~~~~~~~~~~~~~~~~~
+
+.. autoclass:: eth.vm.forks.petersburg.computation.PetersburgComputation
+  :members:
+
+
+Istanbul
+----------
+
+IstanbulVM
+~~~~~~~~~~~~
+
+.. autoclass:: eth.vm.forks.istanbul.IstanbulVM
+  :members:
+
+IstanbulState
+~~~~~~~~~~~~~~~
+
+.. autoclass:: eth.vm.forks.istanbul.state.IstanbulState
+  :members:
+
+IstanbulComputation
+~~~~~~~~~~~~~~~~~~~~~
+
+.. autoclass:: eth.vm.forks.istanbul.computation.PetersburgComputation
+  :members: