Add `semanage` command to RHEL install docs page

[srb3]

Where is the problem?

https://docs.konghq.com/gateway/2.7.x/install-and-run/rhel/

What happened?

A customer was installing Kong onto a RHEL system with SELINUX enabled. After installation they ran some tests and left the system for a while. However, during this time the logs filled up the disk. It turns out that the logrotate scripts provided by the Kong RPM will fail to run if SELINUX is enforcing.

In order to get logrotate to work correctly for the Kong logs the customer used the following command:

semanage fcontext -a -t var_log_t '/usr/local/kong/logs(/.*)?'
restorecon -R -v /usr/local/kong/logs

What did you expect to happen?

We should document running the commands:

semanage fcontext -a -t var_log_t '/usr/local/kong/logs(/.*)?'
restorecon -R -v /usr/local/kong/logs

For RedHat based systems, as these are the most likely to have SELINUX enabled.

Code of Conduct and Community Expectations

• [X] I agree to follow this project's Code of Conduct
• [X] I agree to abide by the Community Expectations