docs: add missing types, prefer pnpm, fix various typos, discourage using payload from import

[AlessioGr]

• Adds missing types, especially the Where type. Will be helpful for people to see that they can type their queries like that
• Mention pnpm first and prefer pnpm > npm > yarn throughout docs
• Add payload to function arguments in examples to discourage people from doing import payload from 'payload'
• Fix some typos