Documentation (parameters): create API docs

[dreamorosi]

Description of the improvement

Summary of the proposal As a part of our documentation we have a section that focuses on the APIs available. The new utility should feature docstrings that will then populate the corresponding pages of this documentation.

How, where did you look for information This unit of work tracks the activities related to having the API docs for the new utility. On an high level, these are:

• Create docstrings for each class / method / function
• Review content accuracy & wording
• Review visually the docs locally

Missing or unclear documentation https://awslabs.github.io/aws-lambda-powertools-typescript/latest/api/modules/_aws_lambda_powertools_parameters.html

Improvement N/A

Related existing documentation

[N/A](https://awslabs.github.io/aws-lambda-powertools-typescript/latest/api/

Related issues, RFCs

#846