Factual and grammatical corrections to the description of metadata applying parameters during import

[victoryforce]

Darktable changes to be reflected here:

• the new preferences section title (this causes a change in the link anchor on the dtdocs page)
• the new name of the preference and its value, which leads to the appearance of an additional column
• the column label now has the corrected XMP spelling

Grammatical corrections:

• after a dependent introductory clause, we use a comma to separate the introductory clause from the main clause
• we don't use "when" to represent only possible but not certain situations