Refactor citation + tags and update README.md

README.md

docs/build_docs.py

examples/cs101_output/s_tag.py

examples/cs101_output/s_tag_a.py

examples/cs101_output/s_tag_b.py

examples/cs101_students/b_tag.py

examples/cs101_students/f_tag.py

examples/cs101_students/i_tag.py

examples/cs101_students/o_tag.py

examples/cs101_students/s_tag.py

examples/output/citations.py

examples/output/load_references_a.py

examples/output/load_references_b.py

src/snipper/__pycache__/block_parsing.cpython-38.pyc

src/snipper/__pycache__/fix_cite.cpython-38.pyc

src/snipper/__pycache__/fix_s.cpython-38.pyc

src/snipper/__pycache__/snipper_main.cpython-38.pyc

src/snipper/block_parsing.py

src/snipper/fix_s.py

src/snipper/snipper_main.py