[Doc] Explicit package distribution/install details

Hi there,

As I understand from the [linked samples repository](https://github.com/aws-solutions-library-samples/guidance-for-low-code-intelligent-document-processing-on-aws), the constructs here can be installed & used via `pip install amazon-textract-idp-cdk-constructs` - which is nicely logical & matching the GitHub name & etc...

But as a library user I'd never like to *assume* such a thing - in case of some malicious package name squatters somewhere.

So it'd be nice if this repository's README was nice and explicit, up top, about what registries users can install the package from?

If we're trying to save space / keep concise, I think a simple shields.io badge would be sufficient... For e.g. the [constructs](https://github.com/aws/constructs#readme) library does this - and for us it could look like:

[](https://pypi.org/project/amazon-textract-idp-cdk-constructs/) MarkDown Source: `[](https://pypi.org/project/amazon-textract-idp-cdk-constructs/)`

...Or if somebody wanted to be more verbose, perhaps could have an explicit section on 'Installing' too? Like e.g. [Pandas](https://github.com/pandas-dev/pandas#readme), [SageMaker Python SDK](https://github.com/aws/sagemaker-python-sdk#readme), and [Amazon Textract Response Parser](https://github.com/aws-samples/amazon-textract-response-parser/blob/master/src-python/README.md) do

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In particular, I see also that https://www.npmjs.com/package/amazon-textract-idp-cdk-constructs exists and seems like it might be maintained by the repo author(s). **Is that the case?** If so, it'd be great to list that on the readme too for CDK TypeScript users.

The badge could look like [](https://www.npmjs.com/package/amazon-textract-idp-cdk-constructs) `[](https://www.npmjs.com/package/amazon-textract-idp-cdk-constructs)`