Doc: add CLI examples for common non-trivial options

[sidhansu10]

This PR adds concise CLI examples for a small set of commonly confusing options, following the approach discussed in #12098.
Scope: - gdal_translate: -r (bilinear), -projwin
Examples are static .. code-block:: console snippets with brief contextual explanations to keep the change simple and reviewable.
Happy to adjust scope or format based on feedback.

[dbaston]

Examples should be placed in the "examples" section of the page and referenced from the option documentation.

[jratike80]

For my mind we should concentrate on the new gdal CLI program. In this case raster convert + resize. But hopefully the new, small subcommands are not as confusing as the old CLI programs. Resampling methods are described shortly in https://gdal.org/en/stable/programs/gdal_raster_resize.html#cmdoption-r and in https://gdal.org/en/stable/programs/gdal_raster_reproject.html#cmdoption-r. Considerations about what resampling method to use are partly opinion based and might fit better to some common knowledge base topic. But we do not have such.

[jratike80]

I am not sure is just this exaple makes sense at all. The size remains the same so perhaps no resampling happens and the -r argument does not have any effect. I may be wrong, though.

[sidhansu10]

Thanks for the feedback. I’ve updated the -r example to include an explicit size change so resampling definitely occurs, and adjusted the -projwin option text to reference the Examples section instead of duplicating an inline example. Please let me know if this looks good now.