message: docs(prop.md): fix typo
diff: @@ -626,7 +626,7 @@ Example:
  ```ts
  class Something {
  - @prop({ allowMixed: Severity.ERROR, type: () => mongoose.Schema.Type.Mixed })
  + @prop({ allowMixed: Severity.ERROR, type: () => mongoose.Schema.Types.Mixed })
  public propy?: any;
  }
  