Fix signal name mismatch in doc (#98)

Author: syntaxerror247

demo/project.godot

@@ -8,6 +8,10 @@
 
 config_version=5
 
+[animation]
+
+compatibility/default_parent_skeleton_in_mesh_instance_3d=true
+
 [application]
 
 config/name="godot billing demo"

demo/store.gd

@@ -21,7 +21,7 @@ func _init() -> void:
 	billing_client.connect_error.connect(_on_connect_error)
 	billing_client.query_product_details_response.connect(_on_query_product_details)
 	billing_client.query_purchases_response.connect(_on_query_purchases)
-	billing_client.on_purchase_updated.connect(_on_purchases_updated)
+	billing_client.on_purchase_updated.connect(_on_purchase_updated)
 
 	billing_client.start_connection()
 
@@ -95,7 +95,7 @@ func _on_query_purchases(result: Dictionary) -> void:
 		_process_purchase(purchase, true)
 
 
-func _on_purchases_updated(result: Dictionary) -> void:
+func _on_purchase_updated(result: Dictionary) -> void:
 	if result.response_code != BillingClient.BillingResponseCode.OK:
 		_show_error("Purchase update failed", result.response_code, result.debug_message)
 		return

demo/store_bck.gd

@@ -125,10 +125,10 @@ else:
 	print("response_code: ", result.response_code, "debug_message: ", result.debug_message)
 ```
 
-The result of the purchase will be sent through the `on_purchases_updated` signal.
+The result of the purchase will be sent through the `on_purchase_updated` signal.
 
 ```gdscript
-func _on_purchases_updated(result: Dictionary):
+func _on_purchase_updated(result: Dictionary):
 	if result.response_code == BillingClient.BillingResponseCode.OK:
 		print("Purchase update received")
 		for purchase in result.purchases:
@@ -140,7 +140,7 @@ func _on_purchases_updated(result: Dictionary):
 
 ### Processing a purchase item
 
-The `query_purchases_response` and `on_purchases_updated` signals provide an array of purchases in Dictionary format.
+The `query_purchases_response` and `on_purchase_updated` signals provide an array of purchases in Dictionary format.
 The purchase Dictionary includes keys that map to values of the Google Play Billing [Purchase](https://developer.android.com/reference/com/android/billingclient/api/Purchase) class.
 
 Purchase fields:
@@ -259,7 +259,7 @@ You need to acknowledge new subscription purchases, but not automatic subscripti
 If you support upgrading or downgrading between different subscription levels, you need to use `update_subscription()` to call the subscription update flow
 to change an active subscription.
 
-Like `purchase()`, results are returned by the `on_purchases_updated` signal.
+Like `purchase()`, results are returned by the `on_purchase_updated` signal.
 
 These are the parameters of `update_subscription()`: