flatter directory strucure for Python examples

Examples/Python/README.md

-BornAgain usage examples.
-
-This directory contains two sets of Python examples
-that demonstrate how to simulate and fit with BornAgain.
+Examples for using BornAgain through the Python API.
 
 Content:
-./simulation - simulation examples
-./fitting    - fitting examples
-./utils      - utilities to plot simulated detector images
\ No newline at end of file
+- sim01...: simulation examples
+- fit51...: fitting examples
+- utils:    utilities to plot simulated detector images
+
+All simulation examples are under continuous test coverage
+through Tests/Functional/Python/PyExamples/CMakeLists.txt.

Examples/Python/fit51_Basic/README.md

+A collection of basic fitting examples.
+
++ Basic fitting tutorial
++ Running fitting consequitively
++ More about minimizer settings

Examples/Python/fit52_Advanced/README.md

+A collection of advanced fitting examples:
+
++ How to fit experimental background.
++ How to fit along slices.
++ How to masks areas on experimental image.
++ How to fit two datasets simultaneously.

Examples/Python/fit55_Specular/README.md

+Fitting specular data.
+
++ Basic demonstration of fitting specular data with BornAgain. GENX simulation results are used as reference data.
++ Fitting live data from XRD reflectometer with BornAgain.