docs(angular): add else if content (#6841)

src/data/roadmaps/angular/content/else-if@ys5untkSppGMFK-VsfuRt.md

@@ -1 +1,8 @@
-# @else if
+# @else if
+
+With the new control flow syntax, you gain `@else if` conditional blocks, something that is not possible with `@ngIf`. This addition makes the control flow syntax close to what we would write with just plain JavaScript.
+
+Visit the following resources to learn more:
+
+- [@official@Angular Official Docs - @if](https://angular.dev/api/core/@if)
+- [@article@Angular @if: Complete Guide](https://blog.angular-university.io/angular-if/)