bug: fix ToC block to adapt to section breaks

[askayastha22]

Fix #87

Test URLs:

• Before: https://main--delta--hlxsites.hlx.page/drafts/alex/import/us/en/skymiles/how-to-earn-miles/earn-with-delta
• After: https://issue-87--delta--hlxsites.hlx.page/drafts/alex/import/us/en/skymiles/how-to-earn-miles/earn-with-delta

[aem-code-sync[bot]]

Hello, I'm Franklin Bot and I will run some test suites that validate the page speed. In case there are problems, just click the checkbox below to rerun the respective action.

• [ ] Re-run PSI Checks

[aem-code-sync[bot]]

Page	Score	PSI Audit	Google
/drafts/alex/import/us/en/skymiles/how-to-earn-miles/earn-with-delta

[aem-code-sync[bot]]

Page	Score	PSI Audit	Google
/drafts/alex/import/us/en/skymiles/how-to-earn-miles/earn-with-delta

[aem-code-sync[bot]]

Page	Score	PSI Audit	Google
/drafts/alex/import/us/en/skymiles/how-to-earn-miles/earn-with-delta