[DOC] It's better to add document about how to upload root CA certificate to quay in a professional way

Description of problem:

Quay official document has a section to guide customer to create a certificate authority and sign a certificate. 

Follow the steps in this section, customer will get certificates like below 

$ ls certificates20220512_144320/
openssl.cnf  rootCA.key  rootCA.pem  rootCA.srl  ssl.cert  ssl.csr  ssl.key

Then the document guide customer to upload ssl.cert and ssl.key to quay pod by config-tool or CLI.

But the ssl.cert file does not include the information about root CA certificate(rootCA.pem). There is no problem to deploy quay and run quay common features. 

But I hit below problem when I tried to mirror image in quay 3.7.0.

Mirror of 7.2-104 failure to repository mirror_test/no_sign Source 'docker://registry.redhat.io/rhel7:7.2-104' failed to sync
time="2022-05-09T02:55:31Z" level=fatal msg="trying to reuse blob sha256:30cf2e26a24f2a8426cbe8444f8af2ecb7023bd468b05c1b6fd0b2797b0f9ff9 at destination: pinging container registry quayregistry-quay-quay-enterprise.apps.whu48az15.qe.azure.devcluster.openshift.com: Get \"https://quayregistry-quay-quay-enterprise.apps.whu48az15.qe.azure.devcluster.openshift.com/v2/\": x509: certificate signed by unknown authority"

There is no step in document to guide customer to upload rootCA.pem to quay. 
Then I run "cat rootCA.pem >> ssl.cert" to attach rootCA.pem to ssl.cert and upload ssl.cert again to resolve this problem. 

It's better to add document about how to upload root CA certificate to quay in a professional way.