Fix links to data sources in bastionzero_db_target resource docs

[ymarcus93]

Must go up a level to reference data sources from a resource doc

Why I think this will fix it?

• Checkout this link: https://github.com/bastionzero/terraform-provider-bastionzero/blob/fix/db-docs/docs/data-sources/bzero_targets.md and click bastionzero_bzero_target link. Then add .md to the url. That link works right now on the live docs page
• Now checkout this link: https://github.com/bastionzero/terraform-provider-bastionzero/blob/fix/db-docs/docs/resources/db_target.md and click on the Linux link. Then add .md to the url. That link works. Hopefully the logic is the same there