Replace Stanford Medicine logo with Stanford Medicine | Biochemistry mark

New 477x84 PNG provided by user. Updated link to biochemistry.stanford.edu
and alt text to reflect the combined branding.

Author: rhiju

_includes/footer.html

@@ -4,8 +4,8 @@
     <div class="footer-bar-teal"></div>
   </div>
   <div class="institutional-logos">
-    <a href="https://med.stanford.edu/" target="_blank" rel="noopener noreferrer external">
-      <img class="logo-stanford-medicine" src="{{ '/assets/images/site/public/nav_logo_stanford_medicine.png' | relative_url }}" alt="Stanford Medicine">
+    <a href="https://biochemistry.stanford.edu/" target="_blank" rel="noopener noreferrer external">
+      <img class="logo-stanford-medicine" src="{{ '/assets/images/site/public/nav_logo_stanford_medicine.png' | relative_url }}" alt="Stanford Medicine — Biochemistry">
     </a>
     <a href="https://www.hhmi.org/scientists/rhiju-das" target="_blank" rel="noopener noreferrer external">
       <img class="logo-hhmi" src="{{ '/assets/images/site/public/nav_logo_hhmi.jpg' | relative_url }}" alt="Howard Hughes Medical Institute">