Fix format appendix

handout/code/3e/data-visualisation-2-dataframe-snippet.py

handout/code/3e/jupyter-code-1-import-snippet.py

handout/code/3e/jupyter-code-1-import.py

handout/code/3e/jupyter-code-2-read.py

handout/code/3e/jupyter-code-3-inspect.py

handout/sections/3e-dataanalytics.typ

handout/sections/3e1-visualise-data.typ

handout/sections/3e2-interactive-explore.typ

handout/sections/a-styleguide.typ

handout/sections/appendix-a-styleguide.typ

handout/sections/appendix-b-cheatsheet.typ

handout/sections/appendix-c-security.typ

handout/sections/appendix.typ