Docs: idempotency docs improvements

[am29d]

What were you searching in the docs?

After few interviews with developers I have collected minor improvements for the idempotency docs. It mostly aims to add missing information for getting started, reduce number of callouts to improve readability.

Is this related to an existing documentation section?

https://docs.powertools.aws.dev/lambda/typescript/latest/utilities/idempotency/

How can we improve?

* add installation command and clarify the aws sdk dynamodb client requirements
* reduce overloaded number of callouts
* fix the example for `eventJmesPath` configuration (does not match between code and event)

Got a suggestion in mind?

No response

Acknowledgment

• I understand the final update might be different from my proposed suggestion, or refused.

[github-actions]

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[github-actions]

This is now released under v1.13.0 version!