Update jsx configuration schema (#7755)

* Update jsx configuration schema

* Add changelog entry

Author: nojaf

CHANGELOG.md

@@ -26,6 +26,8 @@
 
 #### :memo: Documentation
 
+- Update jsx schema configuration. https://github.com/rescript-lang/rescript/pull/7755
+
 #### :nail_care: Polish
 
 #### :house: Internal

docs/docson/build-schema.json

@@ -311,10 +311,9 @@
           "type": "string",
           "description": "JSX module. Either \"react\" for React, or (since v11.1) any valid module name to apply a generic JSX transform."
         },
-        "mode": {
-          "type": "string",
-          "enum": ["classic", "automatic"],
-          "description": "JSX transformation mode"
+        "preserve": {
+          "type": "boolean",
+          "description": "Whether to preserve the JSX in the output. Requires `version` to be set."
         }
       },
       "additionalProperties": false