fix(generateSearch): prevent #undefined in search URLs when heading lacks id

[Mridul012]

Summary

This pull request fixes an issue in the documentation search index generator
(scripts/generateSearch.js) where URLs containing headings without an id
attribute would incorrectly include #undefined in the final link. This caused
broken navigation when clicking certain results in the documentation search.

What was the problem?

The script assumes all <h3> tags have an id and always appends
#${el.prop('id')} to the generated URL. When the id is missing, URLs like the
following were inserted:

What does this PR change?

Adds a null/undefined check before appending URL hash fragments:

• If an id exists → append #id
• If not → return the base page URL

This prevents broken URLs in the search index.

Verification

Verified locally by running:

node scripts/generateSearch.js