chore: JR-317: Corrects attribute name in Getting Started (#513)

Author: bredamc

docs/api-designer/getting-started-api-designer/README.adoc

@@ -245,7 +245,7 @@ endif::[]
 ifdef::qs[]
 [#conclusion]
 ====
-Congratulations! You successfully completed the {api-designer} Getting Started quick start, and are now ready to use the service.
+Congratulations! You successfully completed the {product-api-designer} Getting Started quick start, and are now ready to use the service.
 ====
 endif::[]