Update rst files for python docstring generation (#399)

Summary:
Pull Request resolved: #399

backends/backend_api.py was previously moved to exir/backend/backend_api.py, so we need to update the docstring generation.

Reviewed By: svekars

Differential Revision: D49381377

fbshipit-source-id: 67733a12071d1f26c46149f52b5d4c39aa44eb82

Author: angelayi

docs/source_py/backends.rst

@@ -0,0 +1,52 @@
+exir.backend
+============
+
+exir.lowered_backend_module
+-------------------------------
+
+.. autoclass:: exir.lowered_backend_module.LoweredBackendModule
+   :members:
+   :undoc-members:
+   :show-inheritance:
+
+exir.backend.backend\_api
+-----------------------------
+
+.. automodule:: exir.backend.backend_api
+   :members:
+   :undoc-members:
+   :show-inheritance:
+
+exir.backend.backend\_details
+------------------------------------
+
+.. automodule:: exir.backend.backend_details
+   :members:
+   :undoc-members:
+   :show-inheritance:
+
+exir.backend.compile\_spec\_schema
+-----------------------------------
+
+.. autoclass:: exir.backend.compile_spec_schema.CompileSpec
+   :members:
+   :undoc-members:
+   :show-inheritance:
+
+exir.backend.partitioner
+---------------------------
+
+.. autoclass:: exir.backend.partitioner.DelegationSpec
+   :members:
+   :undoc-members:
+   :show-inheritance:
+
+.. autoclass:: exir.backend.partitioner.PartitionResult
+   :members:
+   :undoc-members:
+   :show-inheritance:
+
+.. autoclass:: exir.backend.partitioner.Partitioner
+   :members:
+   :undoc-members:
+   :show-inheritance:

docs/source_py/exir.backend.rst

@@ -1,9 +1,66 @@
-Reference
+exir
+=======================
+
+Module contents
+---------------
+
+.. automodule:: exir
+   :members:
+   :undoc-members:
+   :show-inheritance:
+
+exir.emit
+---------------------------
+
+.. automodule:: exir.emit
+
+.. autofunction:: emit_program
+
+exir.error
+----------------------------
+
+.. automodule:: exir.error
+   :members:
+   :undoc-members:
+   :show-inheritance:
+
+exir.memory
+-----------------------------
+
+.. automodule:: exir.memory
+   :members:
+   :undoc-members:
+   :show-inheritance:
+
+exir.memory\_planning
+---------------------------------------
+
+.. automodule:: exir.memory_planning
+   :members:
+   :undoc-members:
+   :show-inheritance:
+
+exir.pass\_base
+-------------------------------------------
+
+.. automodule:: exir.pass_base
+   :members:
+   :undoc-members:
+   :show-inheritance:
+
+exir.pass\_manager
+-------------------------------------------
+
+.. automodule:: exir.pass_manager
+   :members:
+   :undoc-members:
+   :show-inheritance:
+
+Subpackages
 -----------
 
 .. toctree::
-   :maxdepth: 1
-   :caption: API
+   :maxdepth: 4
 
-   exir
-   backends
+   exir.backend
+   exir.passes