code: function updateState( state, domainName, data ) {
  	const command = {
  		[ domainName ]: {
  			$set: Object.assign( {}, state[ domainName ] || initialDomainState, data ),
  		},
  	};
  
  	return update( state, command );
  }
docs: @desc Updates name servers entry for given domain.
  
  @param {Object} [state] Current state.
  @param {string} [domainName] Domain name.
  @param {Object} [data] Domain name servers data.
  @return {Object} New state