Update python notebooks to comply with notebook editorial guidelines

[pablo-gar]

Motivation

We have editorial guidelines that notebooks have to follow

https://github.com/chanzuckerberg/cellxgene-census/blob/main/docs/cell_census_notebook_guidelines.md

Definition of Done

Update all python notebooks to adhere to guidelines

Tasks

• comp_bio_census_info.ipynb
• comp_bio_data_integration_scvi.ipynb
• comp_bio_explore_and_load_lung_data.ipynb
• comp_bio_normalizing_full_gene_sequencing.ipynb
• comp_bio_query_data_and_metadata.ipynb
• census_axis_query.ipynb
• census_compute_over_X.ipynb
• census_dataset_presence.ipynb
• census_datasets.ipynb
• census_query_extract.ipynb
• census_rank_gene_groups.ipynb
• census_summary_cell_counts.ipynb

[pablo-gar]

Completed #377