Updated install win10.md instructions

[craigloewen-msft]

I updated the install win10.md instructions. Specifically I added these changes:

• Changed the commands from PowerShell scripts to always use dism
• Adjusted the ordering and wording to (hopefully) more clearly instruct users to skip ahead if they only want WSL 1 and keep on reading for WSL 2
• Moved the 'set WSL 2 as your default' command up higher in the page.
• Removed some redundant links and notes to the manual install packages and notes about being on build 16215 or higher.
• Added a 'Further Resources' section at the bottom that goes over how to check your WSL version. We can expand this in the future to link to the getting started guides.

Let me know what you think!

[opbld31]

Docs Build status updates of commit c676af5:

✅ Validation status: passed

File	Status	Preview URL	Details
WSL/install-win10.md	✅Succeeded

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