Update testscript/doc.go

Co-authored-by: Daniel Martí <mvdan@mvdan.cc>

testscript/doc.go

@@ -209,7 +209,7 @@ The predefined commands are:
     Attach the next exec command to a controlling pseudo-terminal, and use the
     contents of the given file as the raw terminal input. If -stdin is specified,
     also attach the terminal to standard input.
-    Note that this does n ot attach the terminal to standard output/error.
+    Note that this does not attach the terminal to standard output/error.
 
   - [!] ptyout [-count=N] pattern
     Apply the grep command (see above) to the raw controlling terminal output