rearrange scorer code and add comments

Author: adqm

Doc/search_scorer.js

@@ -1,24 +1,34 @@
 var Scorer = {
   score: function (result) {
     let [docname, title, anchor, descr, score, filename] = result;
-    if (docname == "library/stdtypes" || docname == "library/functions") {
+
+    // boost the score of built-in functions and types
+    const builtinPages = ["library/stdtypes", "library/functions"];
+    if (builtinPages.includes(docname)) {
       score += 10;
     }
+
     return score;
   },
 
+  // all values below this line are the Sphinx defaults
+
+  // Additive scores depending on the priority of the object
+  // Priority is set by object domains
+  // (see https://www.sphinx-doc.org/en/master/extdev/domainapi.html)
   objPrio: {
     0: 15,
     1: 5,
     2: -5,
   },
   objPrioDefault: 0,
 
-  objNameMatch: 20,
-  objPartialMatch: 6,
+  objNameMatch: 11, // score if object's name exactly matches search query
+  objPartialMatch: 6, // score if object's name contains search query
+
+  title: 15, // score if title exactly matches search query
+  partialTitle: 7, // score if title contains search query
 
-  title: 15,
-  partialTitle: 7,
-  term: 5,
-  partialTerm: 2,
+  term: 5, // score if a term exactly matches search query
+  partialTerm: 2, // score if a term contains search query
 };