Update documentation to list global as the only supported location for logging resource LogScope

[tyh2333]

Only updating the public doc to make global the only supported location for logging resource LogScope.

We only support global for logging resource LogScope, so updating the public doc to reflect that.
The error handling will be added in a follow up PR since a test is broken by a different service and I'm not able to test it.

Error:
google-beta/services/compute/data_source_google_compute_region_instance_group_manager.go:28:30: undefined: tpgresource.ParseRegionalInstanceGroupManagersFieldValue
make: *** [GNUmakefile:29: vet] Error 1

[github-actions]

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[modular-magician]

Hi there, I'm the Modular magician. I've detected the following information about your changes:

Diff report

Your PR generated some diffs in downstreams - here they are.

google provider: Diff ( 2 files changed, 2 insertions(+), 2 deletions(-))
google-beta provider: Diff ( 2 files changed, 2 insertions(+), 2 deletions(-))

[modular-magician]

Tests analytics

Total tests: 77
Passed tests: 75
Skipped tests: 2
Affected tests: 0

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[SarahFrench]

Thanks for making this fix!