Add the 51Did creator context web example

fiftyone_pipeline_cloudrequestengine/readme.md

@@ -19,6 +19,18 @@ This package uses the `engines` class created by the `fiftyone-pipeline-engines`
 * A `Cloud Request Engine` which calls the 51Degrees cloud service to fetch properties and metadata about them based on a provided resource key. Get a resource key at https://configure.51degrees.com/?utm_source=github&utm_medium=readme&utm_campaign=pipeline-python&utm_content=fiftyone_pipeline_cloudrequestengine-readme.md&utm_term=this-package-fiftyone_pipeline_cloudrequestengine
 * A `Cloud Engine` template which reads data from the Cloud Request Engine.
 
+## Pointing the engine at another host
+
+The engine calls `https://cloud.51degrees.com/api/v4/` unless told
+otherwise. Set the `FOD_CLOUD_API_URL` environment variable, or pass
+`cloud_endpoint` in the engine settings, to the API base of another
+host including the `/api/v4/` segment. A host other than
+cloud.51degrees.com would be used to (a) use an on premise web server,
+or (b) use a privately hosted version of the 51Degrees cloud for
+performance reasons. This is the private hosting option of the cloud
+service, and both run the same service, so code written against one
+works unchanged against the other.
+
 It is used by the cloud versions of the following 51Degrees engines:
 
 - [**fiftyone_devicedetection**](https://pypi.org/project/fiftyone-devicedetection/) - Get details about the devices accessing your web page

fiftyone_pipeline_cloudrequestengine/src/fiftyone_pipeline_cloudrequestengine/cloudrequestengine.py

@@ -76,6 +76,14 @@ def __init__(self, settings = {}):
             self.resource_key = settings["resource_key"]
 
 
+        # The endpoint is the cloud_endpoint setting, then the
+        # FOD_CLOUD_API_URL environment variable, then
+        # cloud.51degrees.com. A host other than cloud.51degrees.com
+        # would be used to (a) use an on premise web server, or (b) use
+        # a privately hosted version of the 51Degrees cloud for
+        # performance reasons. That is the private hosting option of
+        # the cloud service, and both run the same service, so callers
+        # work unchanged against either.
         if "cloud_endpoint" in settings:
             self.baseURL = settings["cloud_endpoint"]
         else: