fix: doc: Recommend system timezone in UTC

Closes: #40090
11 jobs for m12_issue40090_system_utc in 10 minutes and 15 seconds (queued for 2 seconds)
latest
Status Name Job ID Coverage
  Test
passed python310 #26665

00:09:12

passed python36 #26657

00:07:06

passed python37tor035 #26658

00:07:00

passed python37tor045 #26659

00:08:28

passed python37tor046 #26660

00:07:26

passed python37tormaster #26661

00:08:08

passed python37torstable #26662

00:06:57

passed python38 #26663

00:07:09

passed python39 #26664

00:06:53

 
  Deploy
passed pages #26666

00:01:01

passed pages:deploy

00:00:00