Incorrect documentation for north shutdown API

[jchabod]

In the page https://fledge-iot.readthedocs.io/en/develop/plugin_developers_guide/04_north_plugins.html#c-c-plugins , there is a probable mistyping in example for plugin_shutdown (in C/C++ part)

uint32_t plugin_shutdown(PLUGIN_HANDLE handle)
probably should be
void plugin_shutdown(PLUGIN_HANDLE handle)

[Mark Riddoch]

Thanks - I will get that updated.

[Mark Riddoch]

Fixed in develop branch