Clarify `Merge Request Approvals` in the Import Documentation

Problem to Solve

In the import documentation it's suggested that approvals are included when importing. This term is vague and creates a situation where users might expect that approval rules and all their configuration are imported. This is compounded when the project template functionality uses the importer.

Proposal

We should update the documentation to be more clear on exactly what aspects of approvals are imported.

Additional Details

• doc/user/project/import/bitbucket_server.md uses approvals
• doc/user/project/settings/import_export.md uses approvers and approvals
• doc/user/group/import/index.md uses approvers

In all cases we’re importing the same thing, which are whatever the things highlighted in the screencap