fix object in array state react code example

Example 1: react native update state array of objects

let markers = [ ...this.state.markers ];
markers[index] = {...markers[index], key: value};
this.setState({ markers });

Example 2: react native update state array of objects

let newMarkers = markers.map(el => (
      el.name==='name'? {...el, key: value}: el
))
this.setState({ markers });