doc-generator - allow subset to filter supported URIs

[jautor]

Subset mode doesn't allow for filtering the list of supported URIs - since many schemas can appear in multiple locations in the resource tree, and a particular implementation will almost certainly only support a "subset" of those, the tool should allow a customized list. Suggest both an additive and subtractive method for ease of editing: include_uris - show only these URIs in place of the uris from schema. exclude_uris - show the uris from schema except for this list.

[jautor]

This is probably covered now by the new config file option excluded_schema_uris which applies globally and uses string matching. That likely covers the use case as it's actually simpler to scrub out whole sub-trees with a single entry - which probably aligns to a subset output anyway.