Further clarify the two line intersection methods

[AdriaandeJongh]

Geometry2D.line_intersects_line was wonderfully clarified in #92001 but when I looked for intersecting two line segments today it took me way more time than I dare to admit until I found out about Geometry2D.segment_intersects_segment – I figured partly because the docs for line_intersects_line only mention the method's limitation and not the alternative, but also because the description for segment_intersects_segment never even mentions the word 'line'. This simple PR fixes both.