Port of s_tag and readme.md work

README.md

docs/README.jinja.md

docs/build_docs.py

example/__pycache__/load_references.cpython-38.pyc

example/citations.py

example/exercise1.py

example/latex/br.pdf

example/latex/index.aux

example/latex/index.bbl

example/latex/index.blg

example/latex/index.log

example/latex/index.out

example/latex/index.pdf

example/latex/index.synctex.gz

example/latex/index.tex

example/latex/library.bib

example/load_references.py

example/output/citations.py

example/output/load_references_a.py

example/output/load_references_b.py