Fixed typos in README.md

[teddy5518]

Hello,

I have fixed typo in 4.2 to better doc clarity. The # in the word block does not have any meaning, and is not used throughout the document. Thus, I wanted to suggest to change Array#push to Array.push so that it increases readability and matches existing wording style such as 4.4's Array.from .

Thank you

cc. @ljharb

[teddy5518]

Thank you for the knowledge! As a developer who is learning a lot from this style guide, I really appreciate your hard work and feedback. Thank you. :)