docs: correct api route in search api

[jouwdan]

This pull request is for: (mark with an "x")

• [ ] examples/*
• [ ] modules/next
• [ ] packages/next-drupal
• [ ] starters/basic-starter
• [ ] starters/graphql-starter
• [x] Other

GitHub Issue: #746 Please add a link to the GitHub issue where this problem is discussed.

• [ ] I need help adding tests. (mark with an "x") Code changes need test coverage. If you don't know how to make tests, check this box to ask for help.

Describe your changes

Corrects API route in docs for implementing search api

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