README.md - add tip on the API docs

You can view it via localhost.

README.md

@@ -2,6 +2,10 @@
 
 The Izuma Edge provisioning (pep) tool lets you automate the gateway provisioning flow. For more information, please see the [documentation](https://developer.izumanetworks.com/docs/device-management-edge/latest/provisioning/index.html).
 
+## API documentation
+
+You can view the API documentation (swagger) for the pep-server via http://localhost:5151/docs/ once your docker is running.
+
 ## Tests
 
 Run `factory-configurator-client-example`, if it is not installed, follow [the document about building the FCC example on native Linux](https://developer.izumanetworks.com/docs/device-management-provision/latest/ft-demo/building-demo.html#native-linux) for the detailed steps. Below are the quick steps that install the program. For example, in the []`meta-edge`](https://github.com/PelionIoT/meta-edge) project you can find the precompiled binary located at `/edge/system/bin/factory-configurator-client-armcompiled.elf`.