Merge pull request #53 from spacetelescope/fix_notebook_launch_buttons

Fix bug preventing 'colab' and 'binder' launch menu buttons from opening Jupyter notebooks correctly

_config.yml

@@ -29,7 +29,7 @@ bibtex_bibfiles:
 # Information about where the book exists on the web
 repository:
   url: https://github.com/spacetelescope/mast_notebooks  # Online location of your book
-  path_to_book: notebooks  #Optional path to your book, relative to the repository root
+  # path_to_book: notebooks  #Optional path to your book, relative to the repository root
   branch: main  # Which branch of the repository should be used when creating links (optional)
 
 launch_buttons: