doc add note to clarify markers in the doc

Author: camilamacedo86

docs/book/src/reference/markers/crd-validation.md

@@ -6,4 +6,16 @@ schema option.
 
 See [Generating CRDs](/reference/generating-crd.md) for examples.
 
+<aside class="note">
+<h1>Understanding Marker Grouping in Documentation</h1>
+
+Certain markers may seem duplicated. However, these markers are grouped based on their context of use
+— such as fields, types, or arrays. For instance, a marker like `+kubebuilder:validation:Enum` can be applied to
+individual fields or array items, and this flexibility is reflected in the documentation.
+
+The grouping ensures clarity by showing how the same marker can be reused for different purposes.
+
+</aside>
+
+
 {{#markerdocs CRD validation}}