docs: update ngssc.json entry in README

Author: kyubisation

README.md

@@ -181,11 +181,10 @@ nginx -g 'daemon off;'
 
 ### ngssc.json
 
-The package provides a JSON schema: `ngssc.schema.json",`
+The ngssc.json will be generated by the ngsscbuild builder.
 
 ```javascript
 {
-  "$schema": "./node_modules/angular-server-side-configuration/ngssc.schema.json", // Optional
   "variant": "process",           // Either "process" or "NG_ENV".
   "environmentVariables": [],     // Detected environment variables.
   "filePattern": "**/index.html"  // File pattern in which environment variables should be inserted.