Clean up README examples, update to v3 version of SDK

[monde]

Describe the bug?

The README needs to be updated to reference v3 version of the SDK.

Also, take this opportunity to clean up the README in general.

What is expected to happen?

Have a concise and accurate README.

What is the actual behavior?

v2 SDK is obsolete and still referenced.

Reproduction Steps?

Read the README.

Additional Information?

No response

Golang Version

any

SDK Version

any

OS version

No response

[github-actions]

This issue has been marked stale because there has been no activity within the last 14 days. To keep this issue active, remove the stale label.

[github-actions]

This issue has been marked stale because there has been no activity within the last 14 days. To keep this issue active, remove the stale label.

[duytiennguyen-okta]

This is update via #427