Add support of interval role in chart Codeinwp/visualizer-pro#258

Author: girishpanchal30

classes/Visualizer/Render/Sidebar/Google.php

@@ -148,6 +148,7 @@ protected function _renderRoleField( $index ) {
 				'scope' => esc_html__( 'Scope', 'visualizer' ),
 				'style' => esc_html__( 'Style', 'visualizer' ),
 				'tooltip' => esc_html__( 'Tooltip', 'visualizer' ),
+				'interval' => esc_html__( 'Interval', 'visualizer' ),
 			),
 			sprintf( esc_html__( 'Determines whether the series has to be used for a special role as mentioned in %1$shere%2$s. You can view a few examples %3$shere%4$s.', 'visualizer' ), '<a href="https://developers.google.com/chart/interactive/docs/roles#what-roles-are-available" target="_blank">', '</a>', '<a href="https://docs.themeisle.com/article/1160-roles-for-series-visualizer" target="_blank">', '</a>' )
 		);