Merge pull request #9367 from ckeditor/i/9364

Docs: Enable language auto-detection in the WProofreader demo. Closes #9364.

docs/_snippets/features/wproofreader.html

@@ -1,4 +1,7 @@
 <div id="snippet-wproofreader">
-	<p>Typos hapen. We striving to correct them. Hover on the marked words for instant correction suggestions or click the dialoge icon in the bottom right corner to have the whole text proofread at once.</p>
-	<p>You can also paste your own text here to have its spelling and grammar checked.</p>
+	<p>Warsaw is the capital adn largest city of Poland. The metropolis stands on the Vistula River in east-central Poland and its population is officially estimatd at 1.8 million residents within a greater metropolitan area of 3.1 million residents, which makes Warsaw the 7th most-populous capital city in the European Union. Warsaw is an alpha-global city, a major international tourist destination, and a significaant cultural, political, and economic hub. Its historical Old Town was designated a UNESCO World Heritage Site.</p>
+
+	<p>Warschau ist seit 1596 die Hauptstadt Polens und die fl&auml;chenm&auml;&szlig;ig gr&ouml;&szlig;te sowie mit &uuml;ber 1,75 Mio. Einwonern bev&ouml;lkerungsreichste Staddt des Landes. Als eines der wichtigsten Verkehrs-, Wirtschafts- und Handelszentren Mittel- und Osteeuropas genie&szlig;t Warschau gro&szlig;e politische und kulturelle Bedetung. In der Stadt befinden sich zahlreiche Institutionen, Universit&auml;ten, Theater, Museen und Baudenkm&auml;ler.</p>
+
+	<p>Варша́ва является столицей и крупнейшим по населению, и территории городом Польшй. Город стал фактической столицей в 1596 году, коггда после пожара в Вавельском замке в Кракове король Сигизмунд III перёнёс свою резиденцию суда, при этом столичный статус города был подтверждён только в Конституции 1791 года. Через город протекает река Висла, разделяющая город приблизительно поровну.</p>
 </div>

docs/_snippets/features/wproofreader.js

@@ -19,7 +19,7 @@ ClassicEditor
 		plugins: [ ArticlePluginSet, EasyImage, ImageUpload, CloudServices, WProofreader ],
 		wproofreader: {
 			serviceId: '1:Eebp63-lWHbt2-ASpHy4-AYUpy2-fo3mk4-sKrza1-NsuXy4-I1XZC2-0u2F54-aqYWd1-l3Qf14-umd',
-			lang: 'en_AI',
+			lang: 'auto',
 			srcUrl: 'https://svc.webspellchecker.net/spellcheck31/wscbundle/wscbundle.js'
 		},
 		cloudServices: CS_CONFIG,

docs/features/spelling-and-grammar-checking.md

@@ -27,17 +27,17 @@ The proofreader badge in the bottom-right corner shows you the number of mistake
 
 {@snippet features/wproofreader}
 
-## Supported languages
+## Multi-language support
 
-By default the spell checker supports 18 languages: AI-based English (default), American English, Brazilian Portuguese, British English, Canadian English, Canadian French, Danish, Dutch, Finnish, French, German, Greek, Italian, Norwegian Bokmål, Portuguese, Spanish, Swedish and Ukrainian. Grammar checking is available for 16 of them — there is no grammar checking for Finnish and Norwegian.
+As seen in the demo, the spell checking and grammar feature can support multilingual content. If the proofreader language is set to Auto Detect (or the `auto` language is set in the configuration), the feature will automatically recognize the text language and suggest error corrections and grammar specifically for that language.
 
-There are also over 150 additional languages and specialized dictionaries such as medical and legal available for an additional fee. You can check the full list [here](https://webspellchecker.com/additional-dictionaries/).
+{@img assets/img/spellcheck-dictionary.png 800 Setting the spell checker dictionary to auto.}
 
-## Related features
+## Supported languages
 
-There are other language-related CKEditor 5 features you may want to check:
+By default the spell checker supports 18 languages: AI-based English (default), American English, Brazilian Portuguese, British English, Canadian English, Canadian French, Danish, Dutch, Finnish, French, German, Greek, Italian, Norwegian Bokmål, Portuguese, Spanish, Swedish and Ukrainian. Grammar checking is available for 16 of them — there is no grammar checking for Finnish and Norwegian.
 
-* {@link features/language Text part Language}  – Set the language of the selected content part to support multilingual texts.
+There are also over 150 additional languages and specialized dictionaries such as medical and legal available for an additional fee. You can check the full list [here](https://webspellchecker.com/additional-dictionaries/).
 
 ## Installation