Minor syntax change to diagrams.

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

index.html

@@ -2207,7 +2207,7 @@ <h3>Selective Disclosure and Unlinkability</h3>
 labeled verifiers there are dashed arrows back to the circle labeled issuer
 showing collusive data flow.">
           <figcaption style="text-align: center;">
-Verifier to issuer collusion.
+Verifier-to-issuer collusion.
           </figcaption>
         </figure>
         <figure id="verifier-verifier">
@@ -2220,7 +2220,7 @@ <h3>Selective Disclosure and Unlinkability</h3>
 labeled verifiers there are dashed arrows back to other circles labeled issuer
 to show verifier to verifier collusive data flows.">
           <figcaption style="text-align: center;">
-Verifier to verifier collusion.
+Verifier-to-verifier collusion.
           </figcaption>
         </figure>
         <p>