docs: fix layout in new book

[bmorelli25]

Summary

A new, standalone documentation book exists for the APM AWS Lambda extension. This PR fixes the formatting of the book as it no longer follows the formatting of the APM Guide. See the new docs here (before the fixes in this PR).

• For https://github.com/elastic/observability-docs/issues/2207.

[ghost]

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• Start Time: 2022-10-03T23:51:37.370+0000

• Duration: 8 min 56 sec

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Total	166

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