Merge pull request #18666 from edx/aj/a11y/course-outline-verified-cert-btn

Learn About Verified Certificates button on course outline page needs a focus indicator

lms/static/sass/features/_course-sock.scss

@@ -27,6 +27,7 @@
     cursor: pointer;
 
     &.active,
+    &:focus,
     &:hover {
       color: theme-color("success");
       background-color: theme-color("inverse");