[PATCH datacenter-manager 15/16] docs: add section on forcing a new self-signed certificate

[Shannon Sterz <s.sterz@proxmox.com>]

to avoid a warning added previously.

Signed-off-by: Shannon Sterz <s.sterz@proxmox.com>
---
 docs/certificate-management.rst | 31 +++++++++++++++++++++++++++++++
 1 file changed, 31 insertions(+)

diff --git a/docs/certificate-management.rst b/docs/certificate-management.rst
index 652f6ca0..680d8af5 100644
--- a/docs/certificate-management.rst
+++ b/docs/certificate-management.rst
@@ -303,3 +303,34 @@ Test your new certificate, using your browser.
 
 .. [1]
    acme.sh https://github.com/acmesh-official/acme.sh
+
+Manually Renew Self-signed Certificates
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Proxmox Datacenter Manager creates and renews a self-signed certificate if no
+custom or ACME certificate is provided. Older versions issued a certificate
+that was valid for almost 1000 years and did not renew this certificate.
+Beginning with version 1.1, new setups use shorter lived certificates that will
+be regularly renewed. Old self-signed certificates are not replaced in order to
+not disrupt existing setups. In such cases, the following line is
+logged:
+
+.. code-block:: console
+
+   Apr 04 12:17:51 pdm proxmox-datacenter-manager-daily-update[1170]: Self-signed certificate is valid for an excessive amount of time. Please renew it.
+
+To manually renew a certificate, navigate to Configuration -> Certificates.
+Select the certificate ``proxy.pem``. Then click the "Delete Custom
+Certificate" button. Alternatively, you can run the following command:
+
+.. code-block:: shell
+
+   proxmox-datacenter-manager-admin cert update --force
+
+.. WARNING:: Any client using a fingerprint to verify TLS sessions with the
+   server will need to be updated with the new fingerprint.
+
+After manually renewing the certificate once, Proxmox Datacenter Manager will
+start renewing the certificate itself. A certificate will be renewed at the
+earliest 15 days before it expires. Starting from 30 days before it expires,
+notifications will be issued with a reminder about the upcoming renewal.
-- 
2.47.3