Update sidenav and move to API docs

Author: pwseg

src/_data/sidenav/main.yml

@@ -406,8 +406,6 @@ sections:
       title: Generative Audiences
     - path: '/engage/audiences/organization'
       title: Organize Audiences
-    - path: '/engage/audiences/query-language'
-      title: Segment Query Language
 
   - section_title: Journeys
     description: "Learn how to create multi-step Journeys to tailor messages to your users."
@@ -606,6 +604,8 @@ sections:
         title: Public API
       - path: /api/public-api/fql
         title: Destination Filter Query Language
+      - path: '/api/public-api/query-language'
+        title: Segment Query Language
   - section_title: Config API
     slug: api/config-api
     section:

src/engage/audiences/query-language.md renamed to src/api/public-api/query-language.md

@@ -1,6 +1,6 @@
 ---
 title: Segment Query Language Reference
-plan: engage-foundations
+plan: papi
 ---
 
 Segment's query language lets you define audience segments and computed traits. With clear syntax and practical functionality, the language simplifies the process of defining conditions and computations, helping you extract valuable insights from customer data.