Make it clear in the docs how `send_default_pii`detects "personally identifiable information"

[renepupil]

Problem Statement

If this flag is enabled, certain personally identifiable information (PII) is added by active integrations.

For me this raises the question of trustability about this feature, as it is not transparent how you identify PII.

Solution Brainstorm

Can you add there how this information is identified and filtered, maybe reference to the technology or code that does this?