Fix grammar in "phone home" section.

Co-authored-by: Ted Thibodeau Jr <[email protected]>

index.html

@@ -1022,8 +1022,8 @@ <h3>"Phoning Home" Considered Harmful</h3>
 in privacy expectations between <a>holders</a>, <a>issuers</a>,
 <a>verifiers</a>, and other parties expressed in a <a>verifiable credential</a>.
 Phoning home enables <a>issuers</a> to correlate unsuspecting parties with
-the usage of certain <a>verifiable credentials</a> which can violate
-privacy expectations that each entity might have regarding the usage
+the use of certain <a>verifiable credentials</a> which can violate
+privacy expectations that each entity might have regarding the use
 of those credentials. For example, what is expected by the <a>holder</a> to be
 a private interaction between them and the <a>verifier</a> becomes one where
 the <a>issuer</a> is notified of the interaction.