Documentation add timezone and localtime volumes to Docker Guide

[h00000000]

This pull request adds timezone and localtime volumes to the Installation with Docker guide.
Passing these volumes to the container enable gitea to use hosts localtime and timezone.

This is a mandatory change when using the Fail2ban setup to block users after failed login attemts Guide, but it is not described in the documentation. If not set up correctly, a user will experience the following fail2ban behaviour:

Testing with fail2ban-regex will report a valid regex filter.
sudo fail2ban-regex ./gitea/log/gitea.log /etc/fail2ban/filter.d/gitea.conf

On failed authentication attempt, in certain time configurations, fail2ban will not report the failed attempt, neither will increment the failure detection count or proceed to ban the offender after n tries.

This issue was reported in the past (6421), it seems the issue was forgotten but the described problems still apply today.

[h00000000]

In question of the documentation change being added to the docker guide or the fail2ban guide, like the original reported of the issue, i think that using hosts /etc/timezone and /etc/localtime in the container should be considered, even if not using fail2ban

[codecov-io]

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