cmake: improve python pdoc title page

cmake/python.cmake

@@ -235,7 +235,14 @@ endforeach()
 ## Python Packaging  ##
 #######################
 #file(MAKE_DIRECTORY python/${PYTHON_PROJECT})
-file(GENERATE OUTPUT ${PYTHON_PROJECT_DIR}/__init__.py CONTENT "__version__ = \"${PROJECT_VERSION}\"\n")
+configure_file(
+  ${PROJECT_SOURCE_DIR}/ortools/python/__init__.py.in
+  ${PROJECT_BINARY_DIR}/python/__init__.py.in
+  @ONLY)
+file(GENERATE
+  OUTPUT ${PYTHON_PROJECT_DIR}/__init__.py
+  INPUT ${PROJECT_BINARY_DIR}/python/__init__.py.in)
+
 file(GENERATE OUTPUT ${PYTHON_PROJECT_DIR}/algorithms/__init__.py CONTENT "")
 file(GENERATE OUTPUT ${PYTHON_PROJECT_DIR}/bop/__init__.py CONTENT "")
 file(GENERATE OUTPUT ${PYTHON_PROJECT_DIR}/constraint_solver/__init__.py CONTENT "")

ortools/python/__init__.py.in

@@ -0,0 +1,24 @@
+r'''
+# OR-Tools
+
+This is the reference documentation for Google OR-Tools.
+
+This repository contains several component:
+
+ - `ortools.init`,
+
+ - `ortools.algorithms`,
+ - `ortools.graph`,
+
+ - `ortools.linear_solver`,
+ - `ortools.bop`,
+ - `ortools.glop`,
+ - `ortools.pdlp`,
+ - `ortools.constraint_solver`,
+ - `ortools.sat`,
+ - `ortools.packing`,
+ - `ortools.scheduling`,
+'''
+
+__docformat__ = "markdown"  # explicitly disable rST processing above.
+__version__ = "@PROJECT_VERSION@"