@diagram annotation case-sensitivity is not consistent with e.g. @layout annotations #129
Description
The documentation for @layout annotations states that they are case-sensitive, with the example from the documentation @layout[elk.direction] UP being a valid annotation.
For @diagram annotations this is not stated how case sensitivity is handled. Unintuitively, the annotation @diagram[direction] VH does not work, though, as it requires choice option values to be lower-case only, so despite the visible "VH" name for the option, the annotation needs to be @diagram[direction] vh. This is inconsistent with the @layout annotation and not documented in the wiki page.
Which way do you want to use for this annotation? As-is with updated documentation to not break current examples or consistent with the other annotation?