Add note about trailing slash in report path

[ilg]

Is your feature request related to a problem? Please describe:

The only significant issue I had when setting up the plugin was that the plugin defaulted to a path of /data/report while the gateway itself defaulted to a path of /data/report/, and so no data went through.

Describe the solution you'd like:

It might be helpful to add a note in the README that the presence/absence of a trailing slash is significant.

Describe alternatives you've considered:

Alternately, modify the data listening server so that the trailing slash isn't significant.

Additional context:

Thanks for making the plugin.

[spatialdude]

Thanks @ilg that's a good suggestion to note in the README