docs: clarify page parameter version support for folder/dashboard search (#16836)

Adds a version disclaimer for the page parameter in folder/dashboard search docs.

Fixes #16827

docs/sources/http_api/folder_dashboard_search.md

@@ -24,7 +24,7 @@ Query parameters:
 - **folderIds** – List of folder id's to search in for dashboards
 - **starred** – Flag indicating if only starred Dashboards should be returned
 - **limit** – Limit the number of returned results (max 5000)
-- **page** – Use this parameter to access hits beyond limit. Numbering starts at 1. limit param acts as page size.
+- **page** – Use this parameter to access hits beyond limit. Numbering starts at 1. limit param acts as page size. Only available in Grafana v6.2+.
 
 **Example request for retrieving folders and dashboards of the general folder**: