docs: Fix installation instruction in the webpage for the build.sbt file

[gcbeltramini]

What changes are proposed in this pull request?

Make installation instruction in the webpage consistent with the README file in the section related to sbt: https://github.com/microsoft/SynapseML/blob/master/README.md#sbt.

There may be other parts in the https://github.com/microsoft/SynapseML/blob/master/README.md that are not updated in https://microsoft.github.io/SynapseML/docs/getting_started/installation/, but I didn't check anything else.

Does this PR change any dependencies?

• No. You can skip this section.
• Yes. Make sure the dependencies are resolved correctly, and list changes here.

Does this PR add a new feature? If so, have you added samples on website?

• No. You can skip this section.
• Yes. Make sure you have added samples following below steps.

[acrolinxatmsft1]

Acrolinx Scorecards

A minimum Acrolinx score of 80 is required.

Click the scorecard links for each article to review the Acrolinx feedback on grammar, spelling, punctuation, writing style, and terminology.

Article	Acrolinx score	Word and Phrases Score	Correctness Score	Scorecard	Processed
website/docs/getting_started/installation.md	94	100	100	link	✅

More information about Acrolinx

• Install Acrolinx locally for VSCode
• False positives or issues
• Troubleshooting issues with Acrolinx

[github-actions]

Hey @gcbeltramini 👋!
Thank you so much for contributing to our repository 🙌.
Someone from SynapseML Team will be reviewing this pull request soon.

We use semantic commit messages to streamline the release process.
Before your pull request can be merged, you should make sure your first commit and PR title start with a semantic prefix.
This helps us to create release messages and credit you for your hard work!

Examples of commit messages with semantic prefixes:

• fix: Fix LightGBM crashes with empty partitions
• feat: Make HTTP on Spark back-offs configurable
• docs: Update Spark Serving usage
• build: Add codecov support
• perf: improve LightGBM memory usage
• refactor: make python code generation rely on classes
• style: Remove nulls from CNTKModel
• test: Add test coverage for CNTKModel

To test your commit locally, please follow our guild on building from source.
Check out the developer guide for additional guidance on testing your change.

[acrolinxatmsft1]

Acrolinx Scorecards

A minimum Acrolinx score of 80 is required.

Click the scorecard links for each article to review the Acrolinx feedback on grammar, spelling, punctuation, writing style, and terminology.

Article	Acrolinx score	Word and Phrases Score	Correctness Score	Scorecard	Processed
website/docs/getting_started/installation.md	94	100	100	link	✅

More information about Acrolinx

• Install Acrolinx locally for VSCode
• False positives or issues
• Troubleshooting issues with Acrolinx

[acrolinxatmsft1]

Acrolinx Scorecards

A minimum Acrolinx score of 80 is required.

Click the scorecard links for each article to review the Acrolinx feedback on grammar, spelling, punctuation, writing style, and terminology.

Article	Acrolinx score	Word and Phrases Score	Correctness Score	Scorecard	Processed
website/docs/getting_started/installation.md	94	100	100	link	✅

More information about Acrolinx

• Install Acrolinx locally for VSCode
• False positives or issues
• Troubleshooting issues with Acrolinx