Clarify what is meant by "personal data".

index.html

@@ -3091,10 +3091,15 @@ <h2>Keep Personal Data Private</h2>
 
       <p>
 If a [=controller document=] is about a specific individual and is
-public-facing, it is <em>critical</em> that the [=controller documents=]
-contain no personal data. Personal data can instead be transmitted through other
-means such as 1) verifiable credentials [[?VC-DATA-MODEL-2.0]], or 2)
-other private communication channels.
+public-facing, it is <em>critical</em> that the [=controller document=] contains
+no personal biometric or biographical data. While it is true that personal data
+might include pseudonymous information, such as a public cryptographic key,
+publishing that sort of information does not create the same immediate privacy
+dangers as publishing an individual's full name, profile photo, or social media
+account in a [=controller document=]. As an alternative, personal data can
+instead be transmitted through other means such as verifiable credentials
+[[?VC-DATA-MODEL-2.0]] or other data formats sent over private and secure
+communication channels.
       </p>
     </section>