Moving Spark billing docs (#57854)

Co-authored-by: Joe Clark <31087804+jc-clark@users.noreply.github.com>

content/billing/concepts/product-billing/github-spark.md

@@ -1,11 +1,11 @@
 ---
-title: About billing for GitHub Spark
+title: GitHub Spark billing
 intro: 'Learn how {% data variables.product.prodname_spark %} is billed for users.'
 versions:
   feature: spark
 topics:
   - Copilot
-shortTitle: Billing for Spark
+shortTitle: GitHub Spark
 redirect_from:
   - /copilot/concepts/copilot-billing/about-billing-for-github-spark
   - /copilot/concepts/copilot-billing/billing-for-spark

content/billing/concepts/product-billing/index.md

@@ -16,6 +16,7 @@ children:
   - /github-models
   - /github-packages
   - /git-lfs
+  - /github-spark
 contentType: concepts
 ---
 

content/copilot/concepts/billing/index.md

@@ -11,7 +11,6 @@ children:
   - /individual-plans
   - /billing-for-individuals
   - /organizations-and-enterprises
-  - /billing-for-spark
 redirect_from:
   - /managing-copilot/managing-copilot-as-an-individual-subscriber/billing-and-payments
   - /copilot/managing-copilot/understanding-and-managing-copilot-usage

content/copilot/concepts/spark.md

@@ -87,7 +87,7 @@ Benefits include:
 ### Billing
 
 Each natural-language prompt in {% data variables.product.prodname_spark_short %} consumes four premium requests.
-See [AUTOTITLE](/copilot/concepts/billing/billing-for-spark).
+See [AUTOTITLE](/billing/concepts/product-billing/github-spark).
 
 ### Infrastructure