remove file system write of tab.json

vignettes/sc_table_saved.Rmd

@@ -41,18 +41,14 @@ account. Saved tables from other accounts can not be listed or requested.
 To make the table available for later use or for other users of `r STATcubeR`,
 the response can be exported into a json.
 
-```{r}
+```{r, eval = FALSE}
 tab$json$write("tab.json")
 ```
 
-```{r, include=FALSE}
-on.exit(fs::file_delete("tab.json"))
-```
-
 The generated json file contains an API request that can be used in
 `sc_table()`.
 
-```{r}
+```{r, eval = FALSE}
 my_response <- sc_table("tab.json")
 ```