Update docs/Learning-Environment-Design-Agents.md

Co-authored-by: andrewcoh <54679309+andrewcoh@users.noreply.github.com>

docs/Learning-Environment-Design-Agents.md

 
 ### Variable Length Observations
 
-It is possible to have observations be of variable size by using a `BufferSensor`,
+It is possible for agents to collect observations from a varying number of GameObjects by using a `BufferSensor`.
 You can add a `BufferSensor` to your Agent by adding a `BufferSensorComponent` to
 its GameObject.
 The `BufferSensor` can be useful in situations in which the Agent must pay