De-emphasize scheduling priorities

Scheduling priorities are deprecated, so:
- move the page later in the parent topic
- hint that it's not a priority in the sitemap for the live docs

Author: Tim Bannister

content/en/docs/reference/scheduling/policies.md

@@ -1,7 +1,8 @@
 ---
 title: Scheduling Policies
 content_type: concept
-weight: 10
+sitemap:
+  priority: 0.2 # Scheduling priorities are deprecated
 ---
 
 <!-- overview -->