Update README.md

fix default URL desription

Author: ikasarov

README.md

@@ -65,7 +65,7 @@ cf deploy mta-assembly/spring-music.mtar -e config.mtaext
 # Configuration     
 The configuration of the MultiApps CF plugin is done via env variables. The following are supported:
 * `DEBUG=1` - Enables the logging of HTTP requests in `STDOUT` and `STDERRR`.
-* `MULTIAPPS_CONTROLLER_URL=<URL>` - By default, the plugin attempts to deduce the multiapps-controller URL based on the available shared domains. In case of issues, or if you want to target a non-default multiapps-controller instance, you can configure the targeted URL via this env variable.
+* `MULTIAPPS_CONTROLLER_URL=<URL>` - By default, the plugin attempts to deduce the multiapps-controller URL based on the cf api endpoint URL (replaces the first part of the URL with 'deploy-service'). In case of issues, or if you want to target a non-default multiapps-controller instance, you can configure the targeted URL via this env variable.
 * `MULTIAPPS_UPLOAD_CHUNK_SIZE=<POSITIVE_INTEGER>` - By default, large MTARs are not uploaded as a single unit, but are split up into smaller chunks of 45 MBs that are uploaded separately. The goal is to prevent failed uploads due to [gorouter](https://github.com/cloudfoundry/gorouter)'s request timeout. In case the default chunk size is still too large, you can configure it via this environment variable. **The specified values are in megabytes.**
 :rotating_light: Note: The total number of chunks in which an MTAR is split cannot exceed 50, since the multiapps-controller could interpret bigger values as a denial-of-service attack. For this reason, the minimum value for this environment variable is computed based on the formula: `MIN = MTAR_SIZE / 50`
 For example, with a 100MB MTAR the minimum value for this environment variable would be 2, and for a 400MB MTAR it would be 8. Finally, the minimum value cannot grow over 50, so with a 4GB MTAR, the minimum value would be 50 and not 80.