added 6K3I example

src/structure-viewer/index.html

@@ -152,6 +152,10 @@
                 {
                     id: '6C50',
                     info: 'Cross-alpha Amyloid-like Structure alphaAmS'
+                },
+                {
+                    id: '6K3I',
+                    info: 'Salmonella hook in curved state - 66 subunit models'
                 }
             ];