Minor changes in documentation and test

What's Changed

• Cite contextualSpellCheck by @R1j1t in #58
• Improves code highlight by @sobolevn in #63
• Removed optional dependency from requirements.txt by @R1j1t in #65
• Create CITATION.cff by @R1j1t in #66
• update black version by @R1j1t in #74
• Update README.md by @Adheeshk13 in #73

New Contributors

• @sobolevn made their first contribution in #63
• @Adheeshk13 made their first contribution in #73

Full Changelog: v0.4.1...0.4.2