docs: document priority option in announceForAccessibilityWithOptions

[cpruijsen]

Fixes #5258

Documents the priority option of announceForAccessibilityWithOptions(), added in React Native 0.84. The docs listed only queue.

The signature becomes options: {queue?: boolean, priority?: 'low' | 'default' | 'high'}, and the parameters table describes each value with the JSDoc wording from AccessibilityInfo.js. The option is marked iOS only, because the Android implementation ignores options.

Changed in docs/accessibilityinfo.md and in website/versioned_docs/version-0.84 through version-0.87. Version 0.83 and older do not have priority.

Two choices you may want changed:

• The value descriptions sit in the table cell after an <hr/>, as in share.md. They could move into the paragraph above the table.
• iOS applies priority only on iOS 17 and later. I kept to the JSDoc wording and left that out. I can add an "iOS 17+" note.