Update intermediate bucket related doc

docs/source/examples/managed-jobs.rst

@@ -152,6 +152,7 @@ The :code:`MOUNT` mode in :ref:`SkyPilot bucket mounting <sky-storage>` ensures
 Note that the application code should save program checkpoints periodically and reload those states when the job is restarted.
 This is typically achieved by reloading the latest checkpoint at the beginning of your program.
 
+
 .. _spot-jobs-end-to-end:
 
 An End-to-End Example
@@ -455,6 +456,46 @@ especially useful when there are many in-progress jobs to monitor, which the
 terminal-based CLI may need more than one page to display.
 
 
+.. _intermediate-bucket:
+
+Intermediate storage for files
+------------------------------
+
+For managed jobs, SkyPilot requires an intermediate bucket to store files used in the task, such as local file mounts, temporary files, and the workdir.
+If you do not configure a bucket, SkyPilot will automatically create a temporary bucket named :code:`skypilot-filemounts-{username}-{run_id}` for each job launch. SkyPilot automatically deletes the bucket after the job completes.
+
+Alternatively, you can pre-provision a bucket and use it as an intermediate for storing file by setting :code:`jobs.bucket` in :code:`~/.sky/config.yaml`:
+
+.. code-block:: yaml
+
+  # ~/.sky/config.yaml
+  jobs:
+    bucket: s3://my-bucket  # Supports s3://, gs://, https://<azure_storage_account>.blob.core.windows.net/<container>, r2://, cos://<region>/<bucket>
+
+
+If you choose to specify a bucket, ensure that the bucket already exists and that you have the necessary permissions.
+
+When using a pre-provisioned intermediate bucket with :code:`jobs.bucket`, SkyPilot creates job-specific directories under the bucket root to store files. They are organized in the following structure:
+
+.. code-block:: text
+
+  # cloud bucket, s3://my-bucket/ for example
+  my-bucket/
+  ├── job-15891b25/            # Job-specific directory
+  │   ├── local-file-mounts/   # Files from local file mounts
+  │   ├── tmp-files/           # Temporary files
+  │   └── workdir/             # Files from workdir
+  └── job-cae228be/            # Another job's directory
+      ├── local-file-mounts/
+      ├── tmp-files/
+      └── workdir/
+
+When using a custom bucket (:code:`jobs.bucket`), the job-specific directories (e.g., :code:`job-15891b25/`) created by SkyPilot are removed when the job completes.
+
+.. tip::
+  Multiple users can share the same intermediate bucket. Each user's jobs will have their own unique job-specific directories, ensuring that files are kept separate and organized.
+
+
 Concept: Jobs Controller
 ------------------------
 
@@ -505,4 +546,3 @@ The :code:`resources` field has the same spec as a normal SkyPilot job; see `her
   These settings will not take effect if you have an existing controller (either
   stopped or live).  For them to take effect, tear down the existing controller
   first, which requires all in-progress jobs to finish or be canceled.
-