Use CKEditor 5 for description editing.

assets/ckeditor/plugins/extendedMarkdown.js

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+import { Plugin } from 'ckeditor5/src/core';
+import GFMDataProcessor from '@ckeditor/ckeditor5-markdown-gfm/src/gfmdataprocessor';
+
+const ALLOWED_TAGS = [
+	//Common elements
+	'sup',
+	'sub',
+];
+
+/**
+ * The GitHub Flavored Markdown (GFM) plugin with added HTML tags, which are kept in the output. (inline mode)
+ *
+ */
+export default class ExtendedMarkdown extends Plugin {
+
+	/**
+	 * @inheritDoc
+	 */
+	constructor( editor ) {
+		super( editor );
+
+		editor.data.processor = new GFMDataProcessor( editor.data.viewDocument );
+		for (const tag of ALLOWED_TAGS) {
+			editor.data.processor.keepHtml(tag);
+		}
+	}
+
+	/**
+	 * @inheritDoc
+	 */
+	static get pluginName() {
+		return 'Markdown';
+	}
+}

assets/ckeditor/plugins/extendedMarkdownInline.js

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+import { Plugin } from 'ckeditor5/src/core';
+import GFMDataProcessor from '@ckeditor/ckeditor5-markdown-gfm/src/gfmdataprocessor';
+
+const ALLOWED_TAGS = [
+	//Common elements
+	'sup',
+	'sub',
+	'u',
+	'kbd',
+	'mark',
+	'ins',
+	'small',
+	'abbr',
+];
+
+
+/**
+ * The GitHub Flavored Markdown (GFM) plugin with added HTML tags, which are kept in the output. (inline mode)
+ *
+ */
+export default class ExtendedMarkdownInline extends Plugin {
+	/**
+	 * @inheritDoc
+	 */
+	constructor( editor ) {
+		super( editor );
+
+		editor.data.processor = new GFMDataProcessor( editor.data.viewDocument );
+		for (const tag of ALLOWED_TAGS) {
+			editor.data.processor.keepHtml(tag);
+		}
+	}
+
+	/**
+	 * @inheritDoc
+	 */
+	static get pluginName() {
+		return 'Markdown';
+	}
+}

assets/ckeditor/plugins/singleLine.js

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+import Plugin from '@ckeditor/ckeditor5-core/src/plugin';
+
+export default class SingleLinePlugin extends Plugin {
+    init() {
+        const editor = this.editor;
+        const view = editor.editing.view;
+        const viewDocument = view.document;
+
+        //Listen to enter presses
+        this.listenTo( viewDocument, 'enter', ( evt, data ) => {
+            //If user presses enter, prevent the enter action
+            evt.stop();
+        }, { priority: 'high' } );
+
+        //And clipboard pastes
+        this.listenTo( viewDocument, 'clipboardInput', ( evt, data ) => {
+            let dataTransfer = data.dataTransfer;
+
+            //Clean text input (replace newlines with spaces)
+            let input = dataTransfer.getData("text");
+            let cleaned = input.replace(/\r?\n/g, ' ');
+
+            //We can not use the dataTransfer.setData method because the old object is somehow protected
+            data.dataTransfer = new DataTransfer();
+            data.dataTransfer.setData("text", cleaned);
+            
+        }, { priority: 'high' } );
+    }
+}