feat: add possibility to use custom CA with XO

sample.xo-install.cfg

@@ -75,6 +75,11 @@ PRESERVE="3"
 #PATH_TO_HTTPS_CERT=$INSTALLDIR/xo.crt
 #PATH_TO_HTTPS_KEY=$INSTALLDIR/xo.key
 
+# location of CA certificate file.
+# define this if your host certificate is issued by a custom CA and you want XO to trust itself.
+# file can contain multiple certificates
+#PATH_TO_HOST_CA=
+
 # If set to true together with cert/key paths, defined pem key/certificate will be created if neither exists.
 # options: true/false
 #AUTOCERT="false"