DOC: Fix `vtk::ExtractSelectedPolyDataIds` class doc Doxygen syntax
Fix vtk::ExtractSelectedPolyDataIds
class doc Doxygen syntax:
- Use the Doxygen
\code{.cpp}
/\endcode
command to treat the block within them as code and therefore to apply the corresponding formatting. - Do not use backticks when referring to VTK classes: the Doxygen automatic link generation highlights the class names natively.
- Use the Doxygen
\verbatim
/\endverbatim
command to treat the block within them as a verbatim text and therefore to apply the corresponding formatting. - Fix the class name cases so that they can be automatically recognized as such and Doxygen can link them to their class documentation.
Take advantage of the commit to:
- Reword a description for the sake of clearliness.
- Start sentences with capitals.