(docs): misc. updates in `Readme.md`
(docs): misc. updates in `Readme.md`

- add article
- add punctuation
- correct article agreement
- correct spelling

Signed-off-by: Vladislav Doster <90b57cb5de676a59fd763abc710ab99e4d486325@Mastercard.com>

unixorn/zsh-quickstart-kit