Add experimental features to the docs (#2154)

Adding the objects from experimental.cell_space and experimental.devs to the ReadTheDocs documentation.

docs/apis/api_main.md

@@ -9,4 +9,5 @@ space
 datacollection
 batchrunner
 visualization
+experimental
 ```

docs/apis/experimental.md

@@ -0,0 +1,60 @@
+# Experimental
+
+```{eval-rst}
+.. automodule:: experimental.__init__
+   :members:
+```
+
+## Cell Space
+
+```{eval-rst}
+.. automodule:: experimental.cell_space.__init__
+   :members:
+```
+
+```{eval-rst}
+.. automodule:: experimental.cell_space.cell
+   :members:
+```
+
+```{eval-rst}
+.. automodule:: experimental.cell_space.cell_agent
+   :members:
+```
+
+```{eval-rst}
+.. automodule:: experimental.cell_space.cell_collection
+   :members:
+```
+
+```{eval-rst}
+.. automodule:: experimental.cell_space.discrete_space
+   :members:
+```
+
+```{eval-rst}
+.. automodule:: experimental.cell_space.grid
+   :members:
+```
+
+```{eval-rst}
+.. automodule:: experimental.cell_space.network
+   :members:
+```
+
+## Devs
+
+```{eval-rst}
+.. automodule:: experimental.devs.__init__
+   :members:
+```
+
+```{eval-rst}
+.. automodule:: experimental.devs.eventlist
+   :members:
+```
+
+```{eval-rst}
+.. automodule:: experimental.devs.simulator
+   :members:
+```