docs(sagemaker): remove install instructions (aws#23120)

Since the stability of a module has an impact on the npm package thru which a module is released, as part of CDK v2, installation instructions were removed from module-specific README documentation. This change aligns the SageMaker module with this pattern.

closes aws#23119

----

### All Submissions:

* [x] Have you followed the guidelines in our [Contributing guide?](https://github.com/aws/aws-cdk/blob/main/CONTRIBUTING.md)

### Adding new Unconventional Dependencies:

* [ ] This PR adds new unconventional dependencies following the process described [here](https://github.com/aws/aws-cdk/blob/main/CONTRIBUTING.md/#adding-new-unconventional-dependencies)

### New Features

* [ ] Have you added the new feature to an [integration test](https://github.com/aws/aws-cdk/blob/main/INTEGRATION_TESTS.md)?
	* [ ] Did you use `yarn integ` to deploy the infrastructure and generate the snapshot (i.e. `yarn integ` without `--dry-run`)?

*By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license*

packages/@aws-cdk/aws-sagemaker/README.md

@@ -27,20 +27,6 @@ entire machine learning workflow to label and prepare your data, choose an algor
 model, tune and optimize it for deployment, make predictions, and take action. Your models get to
 production faster with much less effort and lower cost.
 
-## Installation
-
-Install the module:
-
-```console
-$ npm i @aws-cdk/aws-sagemaker
-```
-
-Import it into your code:
-
-```typescript
-import * as sagemaker from '@aws-cdk/aws-sagemaker';
-```
-
 ## Model
 
 To create a machine learning model with Amazon Sagemaker, use the `Model` construct. This construct