This function collates a list of all the layer metadata attribution
strings for the layers shown inside a specified map item.
For example:
array_to_string( map_credits( 'Main Map' ) )
Returns a comma separated list of layer credits for layers shown in the
'Main Map' layout item, e.g 'CC-BY-NC, CC-BY-SA'
There's an optional include_layer_names argument you can use
to include layer names before their attribution:
array_to_string( map_credits( 'Main Map',
include_layer_names := true,
layer_name_separator := ': ' ) )
Returns a comma separated list of layer names and their credits for layers
shown in the 'Main Map' layout item,
e.g. 'Railway lines: CC-BY-NC, Basemap: CC-BY-SA'"
