Add a couple of explanatory comments requested in code review

src/annotator/anchoring/html.js

@@ -67,6 +67,7 @@ export function anchor(root, selectors, options = {}) {
   let promise = Promise.reject('unable to anchor');
 
   if (range) {
+    // Const binding assures TS that it won't be re-assigned when callback runs.
     const range_ = range;
     promise = promise.catch(() => {
       let anchor = RangeAnchor.fromSelector(root, range_);

src/annotator/config/settings.js

@@ -16,7 +16,11 @@ import { urlFromLinkTag } from './url-from-link-tag';
  * @prop {(name: string) => unknown} hostPageSetting
  */
 
-/** @param {unknown} value */
+/**
+ * Discard a setting if it is not a string.
+ *
+ * @param {unknown} value
+ */
 function checkIfString(value) {
   return typeof value === 'string' ? value : null;
 }