docs(angular): add complex sequences content (#6560)

src/data/roadmaps/angular/content/complex-sequences@Unjknmb4b2LY-nUVvvF7_.md

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-# Complex Sequences
+# Complex Sequences
+
+Angular lets you animate coordinated sequences, such as an entire grid or list of elements as they enter and leave a page. You can choose to run multiple animations in parallel, or run discrete animations sequentially, one following another.
+
+The functions that control complex animation sequences are:
+
+- `query()`: Finds one or more inner HTML elements.
+- `stagger()`: Applies a cascading delay to animations for multiple elements.
+- `group()`: Runs multiple animation steps in parallel.
+- `sequence()`: Runs animation steps one after another.
+
+Visit the following resources to learn more:
+
+- [@official@Angular Official Docs - Complex Sequences](https://angular.dev/guide/animations/complex-sequences)
+- [@video@Angular Animations: Animating multiple items in parallel](https://www.youtube.com/watch?v=RPdR7HzNQIw)