documentation for plone.app.blob on plone.org needs update

I followed the instructions on plone.org about adding blobfields to content
type [1], but the first example (for ImageField) doesn't work (AttributeError
for getAvailableSizes). I found the answer in a mailing list [2]. Like someone
on the list suggested: i think the doc should be updated. I'd do it myself if i
could.

Kees

[1]
http://plone.org/documentation/manual/upgrade-guide/version/upgrading-plone-3-x-to-4.0/updating-add-on-products-for-plone-4.0/use-plone.app.blob-based-blob-storage,


[2]
http://plone.293351.n2.nabble.com/Plone-4b3-ImageWidget-and-AttributeError-getAvailableSizes-td5076850.html

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