adding mapproxy documentation

README.md

@@ -62,14 +62,15 @@ for the Windows app. If you don't have Wine installed you can create a release b
 
 ## Different map providers
 
-INAV Configurator 2.1 allows to choose between OpenStreetMap and Bing Maps map provider. 
+INAV Configurator 2.1 allows to choose between OpenStreetMap, Bing Maps, and MapProxy map providers. 
 INAV Configurator is shipped **WITHOUT** API key for Bing Maps. That means: every user who wants to use Bing Maps has to create own account, agree to all _Terms and Conditions_ required by Bing Maps and configure INAV Configuerator by himself. 
 
 ### How to choose Map provider
 
 1. Click **Settings** icon in the top-right corner of INAV Configurator
-1. Choose provider: OpenStreetMap or Bing
+1. Choose provider: OpenStreetMap, Bing, or MapProxy
 1. In the case of Bing Maps, you have to provide your own, personal, generated by you, Bing Maps API key
+1. For MapProxy, you need to provide a server URL and layer name to be used
 
 ### How to get Bing Maps API key
 
@@ -84,6 +85,13 @@ INAV Configurator is shipped **WITHOUT** API key for Bing Maps. That means: ever
     1. Application type: Required. Select the application type that best represents the application that will use this key. You can find descriptions of key and application types [here](https://www.microsoft.com/maps/create-a-bing-maps-key.aspx). 
 1. Click the **Create** button. The new key displays in the list of available keys. Use this key to authenticate your Bing Maps application as described in the documentation for the Bing Maps API you are using.
 
+### How to setup a MapProxy server for offline caching and mission planning
+1. Follow process described in [MAPPROXY.md]
+	1. Once you have a working MapProxy server choose MapProxy as your map provider
+	1. Enter MapProxy service URL, eg: http://192.168.20.247/mapproxy/service?
+	1. Enter MapProxy service layer (inav_layer if configured from MAPPROXY.md)
+1. Once completed, you can zoom in on area you will be flying in while connected to the internet in either GPS or Mission Control tab to save the cache for offline use
+
 ## Authors
 
 Konstantin Sharlaimov/DigitalEntity - maintainer of the INAV firmware and configurator.