docs: warn about local sync deletion

Signed-off-by: phernandez <paul@basicmachines.co>

Author: phernandez

content/10.reference/1.cli-reference.md

@@ -259,6 +259,10 @@ bm project remove research --delete-notes
 
 Cloud deletion is accepted asynchronously. Without `--delete-notes`, the project is removed from the hosted database but its cloud files remain. With `--delete-notes`, the background job purges indexed and unindexed objects under the exact project storage prefix before completing the hard delete. Existing cloud snapshots follow their own retention and deletion lifecycle.
 
+::warning
+For a cloud project configured with a local sync path, explicitly passing both `--cloud` and `--delete-notes` also removes that local sync directory. Back up any local files you need before running the command.
+::
+
 ### `bm project default`
 
 Set the default project used as fallback when no project is specified.