Document client requirements for in-place import on Windows. (rebased onto develop)


This is the same as gh-866 but rebased onto develop.

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This PR updates the documentation and explains what option needs to be used to get in-place import working on Windows. It also mentions the limitations of ``ln_rm``. It is a direct result of https://github.com/openmicroscopy/openmicroscopy/pull/2242#commits-pushed-a394dd6.

/cc @joshmoore

                
`POSIX` is a capitalised abreviation.