docs: remove documentation about schema based validation

Author: braaar

README.md

@@ -905,87 +905,7 @@ isBoolean(value);
 
 ## Defining validation schema without decorators
 
-You can define your validation schemas without decorators:
-
-- you can define it in the separate object
-- you can define it in the `.json` file
-
-This feature maybe useful in the cases if:
-
-- are using es5/es6 and don't have decorators available
-- you don't have a classes, and instead using interfaces
-- you don't want to use model at all
-- you want to have a validation schema separate of your model
-- you want beautiful json-schema based validation models
-- you simply hate decorators
-
-Here is an example of using it:
-
-1. Create a schema object:
-
-   ```typescript
-   import { ValidationSchema } from 'class-validator';
-   export let UserValidationSchema: ValidationSchema = {
-     // using interface here is not required, its just for type-safety
-     name: 'myUserSchema', // this is required, and must be unique
-     properties: {
-       firstName: [
-         {
-           type: 'minLength', // validation type. All validation types are listed in ValidationTypes class.
-           constraints: [2],
-         },
-         {
-           type: 'maxLength',
-           constraints: [20],
-         },
-       ],
-       lastName: [
-         {
-           type: 'minLength',
-           constraints: [2],
-         },
-         {
-           type: 'maxLength',
-           constraints: [20],
-         },
-       ],
-       email: [
-         {
-           type: 'isEmail',
-         },
-       ],
-     },
-   };
-   ```
-
-   Same schema can be provided in `.json` file, depend on your wish.
-
-2. Register your schema:
-
-   ```typescript
-   import { registerSchema } from 'class-validator';
-   import { UserValidationSchema } from './UserValidationSchema';
-   registerSchema(UserValidationSchema); // if schema is in .json file, then you can simply do registerSchema(require("path-to-schema.json"));
-   ```
-
-   Better to put this code in a global place, maybe when you bootstrap your application, for example in `app.ts`.
-
-3. Validate your object using validation schema:
-
-   ```typescript
-   import { validate } from 'class-validator';
-   const user = { firstName: 'Johny', secondName: 'Cage', email: '[email protected]' };
-   validate('myUserSchema', user).then(errors => {
-     if (errors.length > 0) {
-       console.log('Validation failed: ', errors);
-     } else {
-       console.log('Validation succeed.');
-     }
-   });
-   ```
-
-   That's it. Here `"myUserSchema"` is the name of our validation schema.
-   `validate` method will perform validation based on this schema
+Schema-based validation without decorators is no longer supported by `class-validator`. This feature was broken in version 0.12 and it will not be fixed. If you are interested in schema-based validation, you can find several such frameworks in [the zod readme's comparison section](https://github.com/colinhacks/zod#comparison).
 
 ## Validating plain objects