docs: add signal forms field state management guide

Author: bencodezen

adev/src/app/routing/sub-navigation-data.ts

@@ -436,19 +436,21 @@ const DOCS_SUB_NAVIGATION_DATA: NavigationItem[] = [
                 label: 'Overview',
                 path: 'guide/forms/signals/overview',
                 contentPath: 'guide/forms/signals/overview',
-                status: 'new',
               },
               {
                 label: 'Form models',
                 path: 'guide/forms/signals/models',
                 contentPath: 'guide/forms/signals/models',
-                status: 'new',
+              },
+              {
+                label: 'Field state management',
+                path: 'guide/forms/signals/field-state-management',
+                contentPath: 'guide/forms/signals/field-state-management',
               },
               {
                 label: 'Comparison with other form systems',
                 path: 'guide/forms/signals/comparison',
                 contentPath: 'guide/forms/signals/comparison',
-                status: 'new',
               },
             ],
           },