Add pnpm script and bash in README.md

[po4tion]

Your package manager did not specify pnpm in the install script even though it was pnpm. This part has been added and the structure has been changed to allow short reading for readability.

As a front-end developer using nextjs, thank you so much for developing an open source project like this.

[tatethurston]

Thanks for the kind words @po4tion I'm glad you find this package helpful