Sources for provinces

See discussion [here](https://github.com/BuildCanada/CanadaSpends/pull/184#issuecomment-3449109615).

For example, BC Spends there are two data sources and we'd like to add some caveats on how we're interpreting the data. The current template doesn't allow us to easily do that.

The page feels over-templated at the moment. Need to have more flexibility to let each province return many source links and change the copy for each.

Start with the discussion in pull request 184 and inspect the current province page template. Determine how source links and explanatory copy are currently supplied. Done means each province can provide multiple source links, caveats about interpretation, and province-specific copy without being constrained by the shared template.

Written by the indexing model from the issue text.