Fix link to device defender SDK in README

[vaibhavsingh1993]

Issue #, if available:

Description of changes:
Fixed link to Device Defender SDK in README

Why is this change necessary:
Fixes README link

How was this change tested:
Manually clicked on the new link to see if the redirect worked.

Any additional information or context required to review the change:

Checklist:

• [v ] Updated the README if applicable
• Updated or added new unit tests
• Updated or added new integration tests
• Updated or added new end-to-end tests
• If your code makes a remote network call, it was tested with a proxy
• [v ] You confirm that the change is backwards compatible

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.

[MikeDombo]

Thank you!