fix(types): correct `ArrayOptions`

[christianhg]

• Removed the comment about layout since it's confusing/wrong. The grid option also works for a string array.
• Added list as a valid layout option. Even though it's the default, it feels weird that you can't specify it manually.
• Removed direction since it doesn't seem to do anything. Maybe it's old?

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I realise that (a) this might be a bold change and (b) I might have no idea what I'm doing since I'm relatively new here, but these changes are based on my observations as I work with the Array schema type and read through https://www.sanity.io/docs/array-type