Fix a few more instances of "usage" use.

index.html

@@ -5555,7 +5555,7 @@ <h3>Patterns of Use</h3>
           </li>
           <li>
 Passing the identifier of a [=credential=] to a centralized revocation server.
-The centralized server can correlate the [=credential|credential's=] use across
+The centralized server can correlate uses of the [=credential=] across
 interactions. For example, if a [=credential=] is used to prove age in this
 manner, the centralized service could know everywhere that [=credential=] was
 presented (all liquor stores, bars, adult stores, lottery sellers, and so on).
@@ -5932,7 +5932,7 @@ <h3>Content Integrity Protection</h3>
 
         <p>
 Section [[[#integrity-of-related-resources]]] of this specification provides an
-optional mechanism for ensuring content integrity of external
+optional mechanism for ensuring the integrity of the content of external
 resources. This mechanism is not necessary for external resources that do not
 impact the [=verifiable credential=]'s security. However, its implementation
 is crucial for external resources where content changes could potentially