Doc(readme): added documentation about the Spell checker feature

README.md

@@ -64,6 +64,7 @@ You can join our [Slack Group] for discussion.
     - [🛠️ Using the embed blocks from `flutter_quill_extensions`](#️-using-the-embed-blocks-from-flutter_quill_extensions)
     - [🔗 Links](#-links-2)
   - [🔄 Conversion to HTML](#-conversion-to-html)
+  - [📝 Spelling checker](#-Spelling-checker)
   - [🌐 Translation](#-translation)
   - [🧪 Testing](#-testing)
   - [👥 Contributors](#-contributors)
@@ -282,6 +283,71 @@ The following packages can be used:
 3. [`flutter_quill_to_pdf`](https://pub.dev/packages/flutter_quill_to_pdf): To convert **Delta** To **PDF**.
 4. [`markdown_quill`](https://pub.dev/packages/markdown_quill): To convert **Markdown** To **Delta** and vice versa.
 
+## 📝 Spelling checker
+
+A spell checker is a software tool or feature integrated into various text processing applications that automatically identifies and corrects spelling errors in a written document. It works by comparing the words in the text against a built-in dictionary. If a word isn't found in the dictionary or doesn't match any known word patterns, the spell checker highlights it as a potential error.
+
+#### Benefits of a spell checker include:
+
+* Improved Accuracy: It helps writers avoid common spelling mistakes, ensuring that the text is free of errors.
+* Time-Saving: Automatically detecting errors reduces the time needed for manual proofreading.
+* Enhanced Professionalism: Correctly spelled words contribute to the overall professionalism of documents, which is crucial in academic, business, and formal writing.
+* Multilingual Support: Many spell checkers support multiple languages, making it easier for users to write accurately in different languages.
+
+> [!IMPORTANT]
+> The spell checker usually does not work as expected in most cases. **Many translations are not supported** such as: `Chinese`, `Japanese`, `Korean`, `Hebrew`, `Arabic`, `Russian`, etc. For now it is a purely **experimental** feature that may have **code that will be modified** in future versions.
+
+#### The translations supported so far are:
+
+* **German** - `de` (may contain errors or missing words)
+* **English** - `en` (currently adding missing translations)
+* **Spanish** - `es` (currently adding missing translations)
+* **French** - `fr` (may contain errors or missing words)
+* **Italian** - `it` (currently adding missing translations)
+* **Norwegian** - `no` (may contain errors or missing words)
+* **Portuguese** - `pt` (may contain errors or missing words)
+* **Swedish** - `sv` (may contain errors or missing words)
+
+_**Note**: **If you have knowledge about any of these available languages or the unsupported ones**, you can make a pull request to add support or add words that are not currently in [simple_spell_checker](https://github.com/CatHood0/simple_spell_checker)_.
+
+In order to activate this functionality you can use the following code:
+
+```dart
+// you can use the language of your preference or directly select the language of the operating system
+final language = 'en'; // or Localizations.localeOf(context).languageCode
+FlutterQuillExtensions.useSpellCheckerService(language);
+```
+
+When you no longer need to have the Spell checker activated you can simply use `dispose()` of the `SpellCheckerServiceProvider` class:
+
+```dart
+// dispose all service and it cannot be used after this
+SpellCheckerServiceProvider.dispose();
+```
+If what we want is to **temporarily deactivate the service** without deleting the values that are already stored in it, we can set `onlyPartial` to `true` so that it only closes the internal `streams` and prevents the dictionaries and values already registered from being reset.
+
+```dart
+// it can be still used by the editor
+SpellCheckerServiceProvider.dispose(onlyPartial: true);
+```
+
+One use of this would be having the opportunity to **activate and deactivate** the service when we want, we can see this in the example that we have in this package, in which you can see that on each screen, we have a button that dynamically activates and deactivates the service. To do this is pretty simple:
+
+```dart
+final bool _isActivatedSpellChecker = false;
+if (!_isActivatedSpellChecker) {
+    FlutterQuillExtensions.useSpellCheckerService(Localizations.localeOf(context).languageCode);
+} else {
+    // close the internal streams without completely closing the service
+    SpellCheckerServiceProvider.dispose(onlyPartial: true);
+    // since onlyPartial is true then we must manually disable the service for it to take effect in the UI
+    SpellCheckerServiceProvider.turnOffService();
+}
+_isActivatedSpellChecker = !_isActivatedSpellChecker;
+```
+
+Open this [page](https://pub.dev/packages/simple_spell_checker) for more information.
+
 ## 🌐 Translation
 
 The package offers translations for the quill toolbar and editor, it will follow the system locale unless you set your