FIX now show usage spec section only to sellers (#171)

Author: laraminones

src/app/shared/header/header.component.html

@@ -195,9 +195,11 @@
                 Analytics
               </a>
             </li>            
-            <li>
-              <button data-cy="usageSpecs" id="usageSpecs" (click)="goTo('/usage-spec')" class="flex w-full justify-left px-4 py-2 hover:bg-gray-100 dark:hover:bg-gray-600 dark:hover:text-white"><fa-icon [icon]="faRuler" class="mr-2"></fa-icon>Usage Spec</button>
-            </li>
+            @if(roles.includes('seller')){            
+              <li>
+                <button data-cy="usageSpecs" id="usageSpecs" (click)="goTo('/usage-spec')" class="flex w-full justify-left px-4 py-2 hover:bg-gray-100 dark:hover:bg-gray-600 dark:hover:text-white"><fa-icon [icon]="faRuler" class="mr-2"></fa-icon>Usage Spec</button>
+              </li>
+            }
             <li>
               <button id="myInventory" (click)="goTo('/product-inventory')"class="flex w-full justify-left px-4 py-2 hover:bg-gray-100 dark:hover:bg-gray-600 dark:hover:text-white"><fa-icon [icon]="faBoxesStacked" class="mr-2"></fa-icon>{{ 'HEADER._inventory' | translate }}</button>
             </li>