fix: custom description, add readme desc

Author: phoenisx

README.md

@@ -202,6 +202,14 @@ This makes SQL Formatter available as a global variable `window.sqlFormatter`.
 - [Vim extension](https://github.com/fannheyward/coc-sql/)
 - [Prettier plugin](https://github.com/un-ts/prettier/tree/master/packages/sql)
 
+We provide **JSON Schema** for `.sql-formatter.json` configuration file, enabling autocompletion and IntelliSense support in editors.
+
+- [JSON Schema link](https://raw.githubusercontent.com/sql-formatter-org/sql-formatter/refs/heads/master/schema.json)
+- **Usage Guides:**
+  - [Using the schema in VSCode](https://code.visualstudio.com/docs/languages/json#_mapping-in-the-user-settings)
+  - [Using the schema in Zed](https://zed.dev/docs/languages/json#schema-specification-via-settings)
+
+
 ### Usage as ESLint plugin
 
 - Inside `eslint-plugin-sql` by using the rule [eslint-plugin-sql#format](https://github.com/gajus/eslint-plugin-sql#format).

json-schema/schema.json renamed to schema.json

@@ -103,7 +103,7 @@
           }
         },
         "custom": {
-          "description": "To allow for :name, @name and/or $name syntax for named placholders.",
+          "description": "An option to implement custom syntax for parameter placeholders. See below for details.",
           "type": "array",
           "items": {
             "type": "object",