[DOCS] Need to put in deprecation warnings to old ISLE7 docs

[ysuarez]

• If applicable, link to the documentation page relevant to your issue below.

Sites like this one below are causing confusion in the community:
https://islandora-collaboration-group.github.io/ISLE/

I suggest that for example, we need to put up a warning label stating that this site refers to the older ISLE7 project, and not the newer Islandora 2 based ISLE project.

This first site (above) was run by the ICG group. Therefore we need to collaborate with someone in that has Github access to make the change directly, or I can put in some PR with the changes that then need to be merged.

Also, there might be other sites or pages that refer to ISLE7 on other Islandora community sites that we can list in this issue as we find them.

• If this is a request for new documentation, where in the existing documentation does this documentation belong?

• Describe your documentation request.

• Which version of islandora are you using?

• What user roles is this documentation intended for?

• What implementations of islandora does this documentation request apply to?

Any related open or closed issues to this bug report?

Screenshots:

[ysuarez]

It was suggested that I reach out to / tag Gavin from BD to accept a PR for this issue.