fix: start-after/end-before order in _rst_include_trim

[JohanKarlbergg]

Hi,

It looks like start-after and end-before may be applied in the wrong order. From how I read the docutils spec, end-before is defined as matching content before the first occurrence of the specified text, but still after any start-after text. That suggests the current behavior might be reversed, though I may be misunderstanding it.

My use case is to include the text between two markers, for example """ and """.

https://docutils.sourceforge.io/docs/ref/rst/directives.html#include-options

[mhils]

Thank you! 😃 Do you want to add a CHANGELOG entry?

[JohanKarlbergg]

Thank you! 😃 Do you want to add a CHANGELOG entry?

Sure :)

[mhils]

Thanks!