examples: Adds a note on how to meet requirements to run the example_…

…test.py

export PYTHONPATH="$IDF_PATH/tools:$IDF_PATH/tools/ci/python_packages"
python -m pip install -r $IDF_PATH/tools/ci/python_packages/ttfw_idf/requirements.txt

It helps to fix the ModuleNotFoundError issue with ttfw_idf and tiny_test_fw modules.

Closes #7815

examples/README.md

@@ -39,6 +39,17 @@ Building an example is the same as building any other project:
 * `idf.py build` to build the example.
 * Follow the printed instructions to flash, or run `idf.py -p PORT flash`.
 
+## Running Test Python Script
+
+Some of the examples have `..._test.py` scripts that are used to test that the example works as expected. These scripts run automatically in the internal test queue. They are not intended to be run by ESP-IDF users but sometimes you may want to run them locally. The following requirements must be met in the IDF python virtual environment.
+
+* ttfw needs to be in the `PYTHONPATH`. Add it like this: `export PYTHONPATH=$PYTHONPATH:$IDF_PATH/tools/ci/python_packages`
+* Install all requirements from `tools/ci/python_packages/ttfw_idf/requirements.txt`: `python -m pip install -r $IDF_PATH/tools/ci/python_packages/ttfw_idf/requirements.txt`
+
+These commands help solve the issue with `ModuleNotFoundError: No module named 'ttfw_idf'` and `ModuleNotFoundError: No module named 'tiny_test_fw'`.
+
+Some examples might fail due to other missing packages. You might need to install them manually: `pip install websocket`.
+
 # Copying Examples
 
 Each example is a standalone project. The examples *do not have to be inside the esp-idf directory*. You can copy an example directory to anywhere on your computer in order to make a copy that you can modify and work with.