fix: Updating proptypes to not warn for multiple children within Block

[ammiranda-isp]

This change updates Block's propTypes to accept both a single child or array of children. Currently Block will issue propType warnings in the console when more than one child is passed to it.

ref: https://stackoverflow.com/a/42122662

[nathanyoung]

According to the react docs, PropTypes.node is

// Anything that can be rendered: numbers, strings, elements or an array
// (or fragment) containing these types.
optionalNode: PropTypes.node,

I'm confused why we would be getting warnings?

[ammiranda-isp]

Hmm based on more digging it looks like you are right that the existing prop-type should cover for one or more children (ref: jsx-eslint/eslint-plugin-react#7). And it looks like the prop-type warning results because some of the children rendered are portal'ed which is an existing bug on prop-types (ref: facebook/prop-types#167). Closing this, thanks for keeping me honest.