installation: linux: redhat-centos.md: Update the suggested configuration of the YUM repo to enable gpg checks on the repository metadata as well for security reasons (#753)

Signed-off-by: justchris1 <[email protected]>

Author: justchris1

installation/linux/redhat-centos.md

@@ -28,11 +28,12 @@ name = Fluent Bit
 baseurl = https://packages.fluentbit.io/centos/7/$basearch/
 gpgcheck=1
 gpgkey=https://packages.fluentbit.io/fluentbit.key
+repo_gpgcheck=1
 enabled=1
 ```
 
-It is best practice to always enable the _gpgcheck_ for security reasons.
-All our packages are signed.
+It is best practice to always enable the _gpgcheck_ and _repo_gpgcheck_ for security reasons.
+We sign our repository metadata as well as all of our packages.
 
 ### GPG key updates