chore: add telemetry opt out notice (#78)

Signed-off-by: Marshall Jackson <[email protected]>

README.md

@@ -73,6 +73,17 @@ def test_something(double_worker: DoubleWorker) -> None:
     # etc.
 ```
 
+## Telemetry
+
+This library collects telemetry data by default. Telemetry events contain non-personally-identifiable information that helps us understand how users interact with our software so we know what features our customers use, and/or what existing pain points are.
+
+You can opt out of telemetry data collection by either:
+
+1. Setting the environment variable: `DEADLINE_CLOUD_TELEMETRY_OPT_OUT=true`
+2. Setting the config file: `deadline config set telemetry.opt_out true`
+
+Note that setting the environment variable supersedes the config file setting.
+
 ## Build / Test / Release
 
 ### Build the package.