refactor Linker and Program Options documentation for attribute level information

[ksimpson-work]

the docstrings for both classes document the members of the dataclass at the top level. ie the docstring for the class is complete and provides a complete description in the built docs html, however the individual attributes do not support mouse hover descriptions.

Move the docstrings from the top level to the individual attributes.

depends on #435 for a cleaner diff

[leofang]

This is done now that #435 is merged. Closing.