fix(typeface): changed the link for plex math resource card (#1369)

src/pages/typography/typeface.mdx

@@ -212,7 +212,7 @@ American Mathematical Society, Version 2.0, 1999/11/15</Caption>
     <ResourceCard
       subTitle="IBM Plex Math"
       aspectRatio="2:1"
-      href="https://fonts.google.com/?query=ibm+plex"
+      href="https://github.com/IBM/plex/releases/tag/%40ibm%2Fplex-math%401.0.0"
       >
 
 ![github logo](../../images/resource-cards/github.png)