[Docs] Link to "Example Diffs" on Public Docs

# Page with link

Although the sections blocks with example Diffs (linking to Phabricator) are wrapped with `` on the markdown, it seems that `docusaurus-plugin-internaldocs-fb/internal` didn't took this in consideration while building the right navigation column and still creates a blind link pointing to the Header: "#example-diffs":


This may happen on other pages as well, but the first I found was on:
https://relay.dev/docs/guides/testing-relay-with-preloaded-queries/#example-diffs