Add simple README.

Author: kylc

python_examples/README.md

@@ -0,0 +1,4 @@
+1. Ensure that BehaviorTree.CPP is build with `BTCPP_PYTHON=ON`.
+2. Add the build directory containing the `btpy_cpp.*.so` Python extension to
+   your `PYTHONPATH`.
+3. Run an example, e.g. `python3 ex01_sample.py`

python_examples/ex01_sample.py

@@ -1,13 +1,7 @@
 #!/usr/bin/env python3
 
 """
-Demo adapted from [1].
-
-To run, ensure that the `btpy_cpp` Python extension is on your `PYTHONPATH`
-variable. It is probably located in your build directory if you're building from
-source.
-
-[1]: https://github.com/BehaviorTree/btcpp_sample
+Demo adapted from [btcpp_sample](https://github.com/BehaviorTree/btcpp_sample).
 """
 
 from btpy import BehaviorTreeFactory, SyncActionNode, NodeStatus, ports

python_examples/ex02_generic_data.py

@@ -2,10 +2,6 @@
 
 """
 Demonstration of passing generic data between nodes.
-
-To run, ensure that the `btpy_cpp` Python extension is on your `PYTHONPATH`
-variable. It is probably located in your build directory if you're building from
-source.
 """
 
 import numpy as np

python_examples/ex03_stateful_nodes.py

@@ -2,10 +2,6 @@
 
 """
 Demonstration of stateful action nodes.
-
-To run, ensure that the `btpy_cpp` Python extension is on your `PYTHONPATH`
-variable. It is probably located in your build directory if you're building from
-source.
 """
 
 import numpy as np

python_examples/ex04_ros_interop.py

@@ -1,11 +1,7 @@
 #!/usr/bin/env python3
 
 """
-Demonstration of stateful action nodes.
-
-To run, ensure that the `btpy_cpp` Python extension is on your `PYTHONPATH`
-variable. It is probably located in your build directory if you're building from
-source.
+Demonstrates interop of BehaviorTree.CPP Python bindings and ROS2 via rclpy.
 """
 
 import rclpy