refactor: migrate to compare/ctor

Author: gururaj1512

…plot/vega/mark/compare/examples/index.js …plot/vega/compare/ctor/examples/index.jslib/node_modules/@stdlib/plot/vega/mark/compare/examples/index.js renamed to lib/node_modules/@stdlib/plot/vega/compare/ctor/examples/index.js lib/node_modules/@stdlib/plot/vega/mark/compare/examples/index.js renamed to lib/node_modules/@stdlib/plot/vega/compare/ctor/examples/index.js

@@ -21,10 +21,10 @@
 /**
 * Compare constructor.
 *
-* @module @stdlib/plot/vega/mark/compare
+* @module @stdlib/plot/vega/compare/ctor
 *
 * @example
-* var Compare = require( '@stdlib/plot/vega/mark/compare' );
+* var Compare = require( '@stdlib/plot/vega/compare/ctor' );
 *
 * var compare = new Compare({
 *     'field': 'amount'