ci: Fix markdown conversion in /demo

.github/workflows/demo-command.yml

@@ -25,7 +25,7 @@ jobs:
             # get body lines, skip first (command)
             $bodyLines = $github.event.client_payload.github.payload.comment.body -split '\r?\n' | Select-Object -Skip 1
             $body = $bodyLines -join "`n"
-            $md = ConvertFrom-Markdown $body
+            $md =  $body | ConvertFrom-Markdown
             $codeBlocks = [Markdig.Syntax.MarkdownObjectExtensions]::Descendants($md.Tokens) | Where-Object { $_ -is [Markdig.Syntax.CodeBlock] }
             if ($codeBlocks) {
               $scriptAst = $codeBlocks | Select-Object -First 1