Update org_policy_policy documentation to make resource definition clearer

[juliorenner]

This PR:

• Updates the documentation to make it explicit that what is required for the resource definition is the project id, not the project name.

The project name may differ from the project id in google. For example, you may have a project ID sandbox-123123 while the project name is sandbox. If in this case using the project name the role creation will fail.

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updated org_policy_policy examples to use project_id instead of project name

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[juliorenner]

cla signed, not sure how to re-run it

[trodge]

/gcbrun

[juliorenner]

@trodge anything missing to be able to move this forward?