adds comment on the api lib to the documentation
### C-API
The C-API provides functions for getting a list of currently loaded account
configurations and an access token for a specific configuration. They can be
-used easily.
+used easily. It is available as a static library at [GitHub](https://github.com/indigo-dc/oidc-agent/releases).
### IPC-API
Alternatively an application can directly communicate with the oidc-agent through UNIX domain sockets. The socket address can be obtained from the environment variable which is set by the agent (```OIDC_SOCK```). The request has to be sent json encoded. We use a UNIX domain socket of type ```SOCK_SEQPACKET```.
