fix(macros/WebExtExamples): update branch name (#9730)

fix: update branch name with `main`

Author: awxiaoxian2020

Diff for: kumascript/macros/WebExtExamples.ejs

@@ -21,7 +21,7 @@ for the header. So if you want the header to be an <h2>, call it with "h2".
 */
 
 const allExamples = await MDN.fetchWebExtExamples();
-const examplesBaseURL = "https://github.com/mdn/webextensions-examples/tree/master/";
+const examplesBaseURL = "https://github.com/mdn/webextensions-examples/tree/main/";
 const desiredHeading = $0 || "h3";
 
 const s_example_addons = mdn.localString({