Update zsc.js

using the first three authors is enough for accurate retrieval

chrome/content/zsc.js

@@ -240,9 +240,13 @@ zsc.generateItemUrl = function(item) {
 
  let creators = item.getCreators();
  if (creators && creators.length > 0) {
+
+ // using the first three authors is enough for accurate retrieval
+ num_creators = creators.length > 3 ? 3 : creators.length;
+
  url += '&as_sauthors=';
  url += creators[0].lastName;
- for (let idx = 1; idx < creators.length; idx++) {
+ for (let idx = 1; idx < num_creators; idx++) {
  url += '+' + creators[idx].lastName;
  }
  }