Add docs for warnings

Author: rvsia

packages/react-renderer-demo/src/components/navigation/schemas/schema.schema.js

@@ -77,6 +77,10 @@ const schemaNav = [
     component: 'validator-mapper',
     linkText: 'Validator mapper'
   },
+  {
+    component: 'validator-warnings',
+    linkText: 'Warnings'
+  },
   {
     subHeader: true,
     title: 'Condition',

packages/react-renderer-demo/src/pages/schema/validator-warnings.md

@@ -0,0 +1,75 @@
+import DocPage from '@docs/doc-page';
+
+<DocPage>
+
+# Validator warnings
+
+If you don't want to block the form from submitting when a validator fails, you can convert the validator into a warning validator.
+
+## 1. Enable warnings
+
+In the field, set `useWarnings` to `true`. This feature can impact performace, so it was made to be opt-in. Please, do not change this value run-time as it could introduce bugs because of React hooks ordering.
+
+```jsx
+{
+    component: 'text-field',
+    useWarnings: true,
+    ...
+}
+```
+
+## 2. Return warning
+
+### Object validator
+
+When you want to return an object validator as a function, just add `warning: true` to its configuration.
+
+```jsx
+{
+    ...,
+    validate: [{ type: 'required', warning: true }]
+}
+```
+
+### Function validator
+
+When using a function as the validator, the function has to return an object with the following format:
+
+```
+{
+    warning: true,
+    error: 'some message'
+}
+```
+
+## 3. Get warning
+
+A warning is stored in `meta.warning`. This value is specific for each field and fields with the same name do not share this. Also, this value is not reachable via `resolveProps` as it's computed just after the `resolveProps` function.
+
+```jsx
+const TextFieldWarning = (props) => {
+  const { input, meta, ...rest } = useFieldApi(props);
+  return (
+    <div>
+      <input {...input} {...rest} />
+      {meta.warning && <div id="warning">{meta.warning}</div>}
+    </div>
+  );
+};
+```
+
+### Convert to error
+
+By default, Data Driven Forms mappers are not supporting showing warnings. However you can convert the warning into an error - set `convertWarningToError` to `true`. This will replace `meta.error` with `meta.warning`, but `valid` etc. will be unchanged.
+
+```jsx
+{
+    name: 'warning-as-error',
+    component: 'text-field',
+    useWarnings: true,
+    convertWarningToError: true,
+    validate: [{type: 'required', warning: true}]
+}
+```
+
+</DocPage>