Remove link to device-behaviour documentation

I would expect the doxygen website to work with either `\ref
Device-behaviour` to link to the section or `\ref modeling-mmio.md` to
link to the file. However the documentation build system was not able to
resolve either of these links at the time of writing this commit.

I tried using `[modeling-mmio.md](../cprover-manual/modeling-mmio.md)`
which should work when viewing the page as markdown locally or through
githubs UI. However this introduced a failure on the doxygen checking PR
job, for which it was non-trivial to add to the list of known warnings,
as the warning message contained an absolute path.

Author: thomasspriggs

doc/architectural/goto-program-transformations.md

@@ -58,7 +58,7 @@ in \ref remove_function_pointers.h
 
 This pass finds pointer dereferences and adds corresponding calls to the
 `__CPROVER_mm_io_r` and `__CPROVER_mm_io_w` modelling functions if they exist.
-See [modeling-mmio.md](Device-behavior) for details of
+See the device behaviour section of `modeling-mmio.md` for details of
 modeling memory-mapped I/O regions of device interfaces. This pass is always
 carried out but will only make changes if one of the modelling functions exist.