update TODO
Add web service client cert / CA documentation

Next step is to add some configuration option handling, to enable the
use of simple yaml lists instead of a long comma separated string as
value for these options.
update TODO
Allow using list in config for certificates

The mxruntime options CACertificates, ClientCertificates and
ClientCertificatePasswords can be specified as list in the yaml
configuration file. The runtime process expects some comma seperated
string, so it's converted to that before sending it. 8-)
Merge certificates documentation and config helper