fix typos in the prepend extension chapter
minor #3957 [Cookbook][Bundles] fix typos in the prepend extension chapter (xabbuh)

This PR was merged into the 2.3 branch.

Discussion
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[Cookbook][Bundles] fix typos in the prepend extension chapter

| Q             | A
| ------------- | ---
| Doc fix?      | yes
| New docs?     | no
| Applies to    | all
| Fixed tickets |

Commits
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ad055ae fix typos in the prepend extension chapter