Update support-for-windows-10.md

[PanuSaukko]

ConfigMgr supports also Windows 10 Enterprise LTSC 2021. I added information about it to the docs. Wasn't sure about Windows 10 IoT Enterprise LTSC 2021. Add it also, if it is supported by ConfigMgr.

[prmerger-automator]

@PanuSaukko : Thanks for your contribution! The author(s) have been notified to review your proposed change.

[learn-build-service-prod]

Learn Build status updates of commit eb2b1d6:

✅ Validation status: passed

File	Status	Preview URL	Details
memdocs/configmgr/core/plan-design/configs/support-for-windows-10.md	✅Succeeded

For more details, please refer to the build report.

For any questions, please:

• Try searching the learn.microsoft.com contributor guides
• Post your question in the Learn support channel

[PalikaSingh]

for Windows 10 IoT Enterprise LTSC 2021 we have to do some testing i will approve the PR for now and based on testing results will add.

[prmerger-automator]

@PanuSaukko : Thanks for your contribution! The author(s) and reviewer(s) have been notified to review your proposed change.

[MandiOhlinger]

@PanuSaukko Hey Panu - This PR has a merge conflict. Can you create a new PR with your recommended changes, if it's still needed? We want you to get credit for any doc changes.

[Yupiter2005]

@PanuSaukko - apologies for the late reply. I noticed that we already got info on that page regarding WIndows 10 LTSC 2021. Still, the page requires further updates.

Let me close this PR then. Sorry for the large delay!