Page to update: https://documentation.magnolia-cms.com/display/DOCS56/Imaging+module
See also description of the parent ticket.
There may be also other little tiny things to update which have changed with the release of 5.5

Old comments on the imaging module:

Version 3.3.1 does not consider (see sourcecode) the properties storeGeneratedImages or validateFileExtension anymore.
(Marc Johnen)
And there may have been others