Add `omero` dependency to instructions

[ehrenfeu]

With the changes from #49, this module has an additional dependency (which is probably omero_ij-<VERSION>-all.jar, correct?).

This should be reflected in the module docstring, as already done for the simple-omero-client JAR:

python-imcflibs/src/imcflibs/imagej/omerotools.py

Lines 1 to 9 in b6e594b

	"""Functions allowing to interact with an OMERO server.
	Contains helpers to parse URLs and / or OMERO image IDs, connect to OMERO and
	fetch images from the server.
	Requires the [`simple-omero-client`][simple-omero-client] JAR to be installed.
	[simple-omero-client]: https://github.com/GReD-Clermont/simple-omero-client
	"""