docs(ingest/mode): add details on authentication/permissions for mode

metadata-ingestion/docs/sources/mode/mode_pre.md

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+### Authentication
+
+See Mode's [Authentication documentation](https://mode.com/developer/api-reference/authentication/) on how to generate an API `token` and `password`.
+
+Mode does not support true "service accounts", so you must use a user account for authentication.
+Depending on your requirements, you may want to create a dedicated user account for usage with DataHub ingestion.
+
+### Permissions
+
+DataHub ingestion requires the user to have the following permissions:
+
+- Have at least the "Member" role.
+- For each Connection, have at least"View" access.
+
+  To check Connection permissions, navigate to "Workspace Settings" → "Manage Connections". For each connection in the list, click on the connection → "Permissions". If the default workspace access is "View" or "Query", you're all set for that connection. If it's "Restricted", you'll need to individually grant your ingestion user View access.
+
+- For each Space, have at least "View" access.
+
+  To check Collection permissions, navigate to the "My Collections" page as an Admin user. For each collection with Workspace Access set to "Restricted" access, the ingestion user must be manually granted the "Viewer" access in the "Manage Access" dialog. Collections with "All Members can View/Edit" do not need to be manually granted access.
+
+Note that if the ingestion user has "Admin" access, then it will automatically have "View" access for all connections and collections.