Doc: added "motivation" page

Author: PierreRaybaut

doc/intro/index.rst

@@ -6,6 +6,7 @@ Getting started
    :caption: Contents:
 
    overview
+   motivation
    installation
    examples
    licenses

doc/intro/motivation.rst

@@ -0,0 +1,51 @@
+.. _motivation:
+
+Motivation
+==========
+
+What are PlotPy V2 advantages over PlotPy V1?
+---------------------------------------------
+
+From a developer point of view, PlotPy V2 is a major overhaul of PlotPy V1:
+
+* Architecture has been redesigned to be more modular and extensible, and more simple.
+* Code quality has been improved introducing `black`, `isort` and typing annotations
+  all over the codebase
+
+.. note::
+    PlotPy V2 is fully typed using Python 3.8+ type annotations.
+    This means that you can use your IDE to get autocompletion and type checking
+    (e.g. with VSCode, Visual Studio, etc.).
+    This is a major improvement when you write code using PlotPy V2:
+    you can rely on the type annotations to understand what a function does
+    and what it returns, and your IDE can help you a lot with autocompletion
+    and type checking.
+
+To sum up, PlotPy V2 is a more modern and more maintainable codebase that will
+allow developers to create plotting applications even more easily than before.
+
+From an end-user point of view, PlotPy V2 is also a significant improvement over
+PlotPy V1:
+
+* PlotPy V2 is more stable and more robust thanks to the new `pytest`-based
+  automated test suite, with a 70% code coverage.
+
+* PlotPy V2 benefits from the backport of many bug fixes and improvements
+  that were made in the guiqwt codebase since PlotPy V1 was released (i.e. from
+  2016 to 2023).
+
+* PlotPy V2 provides tons of new features (e.g. alpha function for better transparency
+  control, refined contour plots, synchronized multiple plots, selection dialog boxes,
+  SVG-based shapes, JSON de/serialization of plot items, new simple way to create
+  plotting widgets with `PlotBuilder`, etc.)
+
+* PlotPy V2 will be maintained and improved in the future, while PlotPy V1 is not
+  maintained anymore. Some significant improvements are already planned for the
+  next releases (e.g. enhanced color maps, new plot items, etc.)
+
+What are PlotPy V2 advantages over guiqwt?
+------------------------------------------
+
+Except from the backporting of bug fixes and improvements that were made in the
+guiqwt codebase since PlotPy V1 was released (i.e. from 2016 to 2023), PlotPy V2
+provides the same advantages over guiqwt as PlotPy V1: see previous section.