fix outer spec to match altered one

spec/ndx-microscopy.extensions.yaml

@@ -302,7 +302,7 @@ groups:
       - height
       - width
       - depths
-      - channels
+      - optical_channels
       shape:
       - null
       - null
@@ -314,12 +314,20 @@ groups:
       dtype:
         reftype: object
         target_type: MicroscopyLightSource
+      dims:
+        - light_sources
+      shape:
+        - null
     - name: optical_channels
       doc: An ordered list of references to MicroscopyOpticalChannel objects containing metadata about the indicator and filters used to collect this data. This maps to the last dimension of `data`, i.e., the i-th MicroscopyOpticalChannel contains metadata about the indicator and filters used to collect the volume at `data[:,:,:,i]`.
       neurodata_type_inc: VectorData
       dtype:
         reftype: object
         target_type: MicroscopyOpticalChannel
+      dims:
+        - optical_channels
+      shape:
+        - null
     links:
     - name: microscope
       doc: Link to a Microscope object containing metadata about the device used to acquire this imaging data.