Fix minor grammatical errors in README

[yrahul3910]

Written to the point. I've made a few grammatical changes throughout the document.

[willdurand]

Thanks @yrahul3910. What's the rule for adding/not adding "the" in a sentence by the way?

[yrahul3910]

Generally you use 'the' before a noun in a sentence when you refer to something specific. It's used when there's a particular thing you want to refer to. For example, you say "Please see the CONTRIBUTING.md file" since there's only one such file.

[willdurand]

Thank you for the explanation! And thank you for the PR!