Remove paragraph about whitespace and Ice. (rebased onto dev_5_0)



This is the same as gh-701 but rebased onto dev_5_0.

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This PR fixes https://trac.openmicroscopy.org.uk/ome/ticket/10378. Since https://github.com/openmicroscopy/openmicroscopy/pull/2174 got merged, there is no need anymore to avoid whitespace in Ice installation paths.