fix(docs): wrap join example in v-pre to fix VitePress build

The inline `{{join " " .WORDS}}` example was parsed as a Vue
interpolation, which broke the website build. Wrap it in <span v-pre>
so it renders literally, matching the existing escaped example in the
same file.

website/src/docs/reference/templating.md

@@ -566,7 +566,7 @@ tasks:
 ```
 
 In pipeline form, `join` receives the list from the left-hand side. The
-equivalent non-pipeline form is `{{join " " .WORDS}}`.
+equivalent non-pipeline form is <span v-pre>`{{join " " .WORDS}}`</span>.
 
 #### Shell Argument Parsing