Update DropBox documentation

[cblackburn]

In fixing #5972 it is apparent that there needs to be additional documentation for users to use config to minimise their chances of duplicate imports. See #7380

[cblackburn]

Proposed documentation additions to,

​https://www.openmicroscopy.org/site/support/omero4/server/fs#section-5

are below. These can be updated when necessary.

Under some circumstances duplicate imports can occur. These are either where there is a delay between the file and any companion files being copied or where there are a large number of files making up a single acquisition. The likelihood of a  duplicate import can be reduced in each case by adjusting the two configuration variables below. In the former case increasing the fileWait time to beyond the delay between copied files. In the latter case increasing the fileBatch size to be greater than the number of acquired files.

The time in seconds that DropBox should wait after being notified of a file before processing a file. This allows for copying delays between companion files. The default is 60 seconds.

        <property name="omero.fs.fileWait"  value="60"/>

----


The number of files in an acquisition that should trigger an import. This parameter is designed to avoid indefinite waits. It should be increased if the usual workflow is to copy in file sets comprising a larg number of files. The default is 10.

        <property name="omero.fs.fileBatch"  value="10"/>

----

        ...
        <property name="omero.fs.fileWait"   value="60;60"/>
        <property name="omero.fs.fileBatch"   value="10;10"/>
        ...

[jburel]

Moved from sprint 2011-12-13 (4)

[jburel]

Moved from sprint 2012-01-03 (5)

[jmoore]

Moved from sprint 2012-01-31 (7)

[jburel]

Moved from sprint 2012-02-14 (8)

[cblackburn]

Delayed change made on the back of the 4.3.4 release.