Improve clarity of label conflict discussion in Prezi 4.7

[azaroth42]

From slack, editors discussion:

Change 4.7 to be clearer about the results of the label conflict between IIIF and Annotation contexts:

... the API overrides the definition from the Annotation model to ensure that labels can consistently be represented in multiple languages, ...

to

... the API overrides the definition from the Annotation model to ensure that labels can consistently be represented in multiple languages by using the [language map construction] [section-4.4].

[kirschbombe]

Language has been updated in the Presi 301 Milestone branch - commit https://github.com/IIIF/api/pull/2094/commits/f2b2212864519abc9362e2a0be093eaf77fc692d