Fix Link in valid_parent_check_plugin.rs (#6584)

# Objective

Link doesn't get to right segment

## Solution

Fix link

Author: DasLixou

crates/bevy_hierarchy/src/valid_parent_check_plugin.rs

@@ -50,7 +50,7 @@ pub fn check_hierarchy_component_has_valid_parent<T: Component>(
             already_diagnosed.insert(entity);
             warn!(
                 "warning[B0004]: {name} with the {ty_name} component has a parent without {ty_name}.\n\
-                This will cause inconsistent behaviors! See https://bevyengine.org/learn/errors/#B0004",
+                This will cause inconsistent behaviors! See https://bevyengine.org/learn/errors/#b0004",
                 ty_name = get_short_name(std::any::type_name::<T>()),
                 name = name.map_or("An entity".to_owned(), |s| format!("The {s} entity")),
             );