Document new functionality in 4.1

[markerikson]

The README needs to be updated to cover:

• Passing an options object to createSelector
• Passing memoizeOptions as an array or direct item
• Customizing equality
• Changing cache size
• Providing a resultEqualityCheck
• TypeScript examples
• New "utils" added to the generated selectors

[markerikson]

At least partly done-ish, but probably could use some more updates.