rmv extra imports (#900)

Co-authored-by: Cody Baker <[email protected]>

docs/user_guide/backend_configuration.rst

@@ -132,7 +132,7 @@ Then we can use this configuration to write the NWB file:
 
 .. code-block:: python
 
-    from neuroconv.tools.nwb_helpers import configure_backend, BACKEND_NWB_IO, configure_and_write_nwbfile
+    from neuroconv.tools.nwb_helpers import configure_and_write_nwbfile
 
     dataset_configurations["acquisition/MyTimeSeries/data"] = dataset_configuration
 
@@ -292,4 +292,4 @@ Which prints out:
 .. note::
 
     You may have noticed that the name of the key for that compression option got lost in translation; this is because
-HDF5 implicitly forces the order of each option in the tuple (or in this case, a scalar).
+    HDF5 implicitly forces the order of each option in the tuple (or in this case, a scalar).