Update file protocol.html

wiki/pages/protocol.html

@@ -100,7 +100,7 @@
                 <span>
                   <small>
                     <a href="#anchor2.2" class="scroll-link d-block w-100"
-                      >Protein espression validation</a
+                      >Protein expression validation</a
                     >
                   </small></span
                 >