Miscellaneous fixes

[vicroms]

• Fix bug in tutorials when setting environment variables in CMD that would make the variable contain quotation marks in its value.
• Fix a missing example snippet in format-manifest.md and clarify that --all option only affects the built-in ports directory (${VCPKG_ROOT}/ports).
• Remove reference to a non-Microsoft repository
• Fix documentation of platform expressions where binary operators && and || were stated to be supported when they are not.

Fixes #318, #323, and #350

[learn-build-service-prod[bot]]

Learn Build status updates of commit 5c281c0:

:white_check_mark: Validation status: passed

File	Status	Preview URL	Details
vcpkg/commands/format-manifest.md	:white_check_mark:Succeeded	View
vcpkg/consume/asset-caching.md	:white_check_mark:Succeeded	View
vcpkg/consume/binary-caching-local.md	:white_check_mark:Succeeded	View
vcpkg/consume/binary-caching-nuget.md	:white_check_mark:Succeeded	View
vcpkg/get_started/get-started-msbuild.md	:white_check_mark:Succeeded	View
vcpkg/get_started/get-started-packaging.md	:white_check_mark:Succeeded	View
vcpkg/get_started/get-started-vs.md	:white_check_mark:Succeeded	View
vcpkg/get_started/get-started.md	:white_check_mark:Succeeded	View
vcpkg/reference/vcpkg-json.md	:white_check_mark:Succeeded	View

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

[prmerger-automator[bot]]

PRMerger Results

Issue	Description
File Change Percent	This PR contains file(s) with more than 30% file change.

[learn-build-service-prod[bot]]

Learn Build status updates of commit 72caeb7:

:white_check_mark: Validation status: passed

File	Status	Preview URL	Details
vcpkg/commands/format-manifest.md	:white_check_mark:Succeeded	View
vcpkg/consume/asset-caching.md	:white_check_mark:Succeeded	View
vcpkg/consume/binary-caching-local.md	:white_check_mark:Succeeded	View
vcpkg/consume/binary-caching-nuget.md	:white_check_mark:Succeeded	View
vcpkg/get_started/get-started-msbuild.md	:white_check_mark:Succeeded	View
vcpkg/get_started/get-started-packaging.md	:white_check_mark:Succeeded	View
vcpkg/get_started/get-started-vs.md	:white_check_mark:Succeeded	View
vcpkg/get_started/get-started.md	:white_check_mark:Succeeded	View
vcpkg/reference/vcpkg-json.md	:white_check_mark:Succeeded	View

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

[prmerger-automator[bot]]

PRMerger Results

Issue	Description
File Change Percent	This PR contains file(s) with more than 30% file change.