vici: flush-certs command flushes certificate cache

When fresh CRLs are released with a high update frequency (e.g.
every 24 hours) or OCSP is used then the certificate cache gets
quickly filled with stale CRLs or OCSP responses. The new VICI
flush-certs command allows to flush e.g. cached CRLs or OCSP
responses only. Without the type argument all kind of certificates
(e.g. also received end entity and intermediate CA certificates)
are purged.

src/libcharon/plugins/vici/README.md

@@ -481,6 +481,19 @@ Load a shared IKE PSK, EAP or XAuth secret into the daemon.
 		errmsg = <error string on failure>
 	}
 
+### flush-certs() ###
+
+Flushes the certificate cache. The optional type argument allows to flush
+only certificates of a given type, e.g. all cached CRLs.
+
+	{
+		type = <certificate type to filter for, X509|X509_AC|X509_CRL|
+												OCSP_RESPONSE|PUBKEY or ANY>
+	} => {
+		success = <yes or no>
+		errmsg = <error string on failure>
+	}
+
 ### clear-creds() ###
 
 Clear all loaded certificate, private key and shared key credentials. This