docs(api): consolidate and clarify contains method documentation (#264)

Remove duplicate contains method section and update description to be more precise about checking both entities and components. Also fix example code references to use contains instead of has for consistency.

docs/api/world.md

@@ -355,46 +355,9 @@ This operation is the same as calling:
 world:target(entity, jecs.ChildOf, 0)
 ```
 
-## contains
-
-Checks if an entity or component (id) exists in the world.
-
-```luau
-function World:contains(
-    entity: Entity,
-): boolean
-```
-
-Example:
-
-::: code-group
-
-```luau [luau]
-local entity = world:entity()
-print(world:contains(entity))
-print(world:contains(1))
-print(world:contains(2))
-
--- Outputs:
--- true
--- true
--- false
-```
-
-```ts [typescript]
-const entity = world.entity();
-print(world.contains(entity));
-print(world.contains(1));
-print(world.contains(2));
-
-// Outputs:
-// true
-// true
-// false
-```
-
 :::
 
+
 ## remove
 
 Removes a component (ID) from an entity
@@ -460,11 +423,11 @@ Example:
 
 ```luau [luau]
 local entity = world:entity()
-print(world:has(entity))
+print(world:contains(entity))
 
 world:delete(entity)
 
-print(world:has(entity))
+print(world:contains(entity))
 
 -- Outputs:
 -- true
@@ -601,7 +564,7 @@ print(retrievedParent === parent) // true
 
 ## contains
 
-Checks if an entity exists and is alive in the world.
+Checks if an entity or component (id) exists and is alive in the world.
 
 ```luau
 function World:contains(