Update docs: mention Docker requirement for db pull (#4553)

* chore(docs): mention Docker requirement for db pull

* Clarify Docker requirement in pull.md

Updated note about Docker requirement for the pull command.

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Co-authored-by: Han Qiao <[email protected]>

Author: magentaqin

docs/supabase/db/pull.md

@@ -4,6 +4,8 @@ Pulls schema changes from a remote database. A new migration file will be create
 
 Requires your local project to be linked to a remote database by running `supabase link`. For self-hosted databases, you can pass in the connection parameters using `--db-url` flag.
 
+> Note this command requires Docker Desktop (or a running Docker daemon), as it starts a local Postgres container to diff your remote schema.
+
 Optionally, a new row can be inserted into the migration history table to reflect the current state of the remote database.
 
 If no entries exist in the migration history table, `pg_dump` will be used to capture all contents of the remote schemas you have created. Otherwise, this command will only diff schema changes against the remote database, similar to running `db diff --linked`.