Remove NIRISS imaging nb from repo; now in jwst-pipeline-notebooks (#266)

Author: haticekaratay

_toc.yml

@@ -81,8 +81,6 @@ parts:
       title: WFSS Spectra - Cross-Correlation Template
     - file: notebooks/NIRISS/NIRISS_WFSS_postpipeline/03_Spatially_resolved_emission_line_map.ipynb
       title: WFSS Spectra - Emission Line Map
-    - file: notebooks/NIRISS/niriss_imaging/niriss-imaging-tutorial.ipynb
-      title: NIRISS Imaging Tutorial
     - file: notebooks/NIRISS/NIRISS_WFSS_advanced/00_niriss_mast_query_data_setup.ipynb
       title: NIRISS MAST
     - file: notebooks/NIRISS/NIRISS_WFSS_advanced/01_niriss_wfss_image2_image3.ipynb