Fix error in markdown/package.nls.json (#44705)

Theere was an extra 'preview' in the message.

extensions/markdown/package.nls.json

@@ -9,7 +9,7 @@
 	"markdown.preview.lineHeight.desc": "Controls the line height used in the markdown preview. This number is relative to the font size.",
 	"markdown.preview.markEditorSelection.desc": "Mark the current editor selection in the markdown preview.",
 	"markdown.preview.scrollEditorWithPreview.desc": "When a markdown preview is scrolled, update the view of the editor.",
-	"markdown.preview.scrollPreviewWithEditor.desc": "When a markdown editor preview is scrolled, update the view of the preview.",
+	"markdown.preview.scrollPreviewWithEditor.desc": "When a markdown editor is scrolled, update the view of the preview.",
 	"markdown.preview.title" : "Open Preview",
 	"markdown.previewFrontMatter.dec": "Sets how YAML front matter should be rendered in the markdown preview. 'hide' removes the front matter. Otherwise, the front matter is treated as markdown content.",
 	"markdown.previewSide.title" : "Open Preview to the Side",
@@ -19,4 +19,4 @@
 	"markdown.showPreviewSecuritySelector.title": "Change Preview Security Settings",
 	"markdown.trace.desc": "Enable debug logging for the markdown extension.",
 	"markdown.refreshPreview.title": "Refresh Preview"
-}
+}