docs: admin-guide: update tiny script for number of taint flags

Account for 2 new taint flags being added by increasing the number of
bits handled by the tiny show-tainted-flags example script.

Fixes: 8eea4e7447 ("taint: Add TAINT_FWCTL")
Fixes: 2852ca7fba ("panic: Taint kernel if tests are run")
Signed-off-by: Randy Dunlap <[email protected]>
Reviewed-by: David Gow <[email protected]>
Signed-off-by: Jonathan Corbet <[email protected]>
Message-ID: <[email protected]>

Documentation/admin-guide/tainted-kernels.rst

@@ -74,7 +74,7 @@ a particular type of taint. It's best to leave that to the aforementioned
 script, but if you need something quick you can use this shell command to check
 which bits are set::
 
-	$ for i in $(seq 18); do echo $(($i-1)) $(($(cat /proc/sys/kernel/tainted)>>($i-1)&1));done
+	$ for i in $(seq 20); do echo $(($i-1)) $(($(cat /proc/sys/kernel/tainted)>>($i-1)&1));done
 
 Table for decoding tainted state
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~