chore: fix base path in examples build for GH pages (thrice) (#635)

### Summary
Continuing from #634 and #633

Hopefully third time is the charm

I did a few more local tests this time and I'm more certain this will
fix all issues

Author: aganders3

packages/core/generate-examples-manifest.js

@@ -36,7 +36,7 @@ function generateExamplesManifest() {
       return {
         id: example.name,
         title: title,
-        path: `/${example.name}/`,
+        path: `${example.name}/`,
         directory: example.name
       };
     });