On Linux use a different example (fixes #18902)

src/vs/workbench/contrib/welcome/walkThrough/browser/editor/vs_code_editor_walkthrough.ts

@@ -56,7 +56,7 @@ app.listen(3000);
 
 ### Line Actions
 Since it's very common to work with the entire text in a line we provide a set of useful shortcuts to help with this.
-1. Copy a line and insert it above or below the current position with kb(editor.action.copyLinesDownAction) or kb(editor.action.copyLinesUpAction) respectively.
+1. <span class="mac-only windows-only">Copy a line and insert it above or below the current position with kb(editor.action.copyLinesDownAction) or kb(editor.action.copyLinesUpAction) respectively.</span><span class="linux-only">Copy the entire current line when no text is selected with kb(editor.action.clipboardCopyAction).</span>
 2. Move an entire line or selection of lines up or down with kb(editor.action.moveLinesUpAction) and kb(editor.action.moveLinesDownAction) respectively.
 3. Delete the entire line with kb(editor.action.deleteLines).