docs: volumes are only supported in ord region (#3057)

The volumes page and tutorial incorrectly listed `ams` (Amsterdam) as a
supported region for volumes and snapshots. Currently only `ord` (Chicago)
supports volumes — the `ams` volume infrastructure is not yet provisioned.

This caused a customer to hit unexplained 503 errors when trying to create
volumes in `ams` following the docs.

### Changes

- `sandbox/volumes.md`: Updated code comments and region field description to
  indicate only `ord` is supported
- `examples/tutorials/volumes.md`: Same fix in the tutorial

Author: avocet-bot

examples/tutorials/volumes.md

@@ -42,7 +42,8 @@ const client = new Client();
 
 ## Provision storage for the cache
 
-Pick a region (`ord` or `ams`) that matches the sandboxes you plan to run.
+Pick a region that matches the sandboxes you plan to run. Currently only `ord`
+(Chicago) supports volumes.
 
 We're going to provide 2 GB of storage for our training cache volume:
 

sandbox/volumes.md

@@ -30,7 +30,7 @@ const client = new Client();
 
 const volume = await client.volumes.create({
   slug: "training-cache",
-  region: "ord", // ord (Chicago) or ams (Amsterdam)
+  region: "ord", // only "ord" (Chicago) is supported today
   capacity: "2GB", // accepts bytes or "1GB"/"512MB" style strings
 });
 
@@ -54,7 +54,7 @@ sdk = DenoDeploy()
 
 volume = sdk.volumes.create(
   slug="training-cache",
-  region="ord",  # ord (Chicago) or ams (Amsterdam)
+  region="ord",  # only "ord" (Chicago) is supported today
   capacity="2GB"  # accepts bytes or "1GB"/"512MB" style strings
 )
 
@@ -78,7 +78,7 @@ sdk = AsyncDenoDeploy()
 
 volume = await sdk.volumes.create(
   slug="training-cache",
-  region="ord",  # ord (Chicago) or ams (Amsterdam)
+  region="ord",  # only "ord" (Chicago) is supported today
   capacity="2GB"  # accepts bytes or "1GB"/"512MB" style strings
 )
 
@@ -95,11 +95,11 @@ print(volume)
 </deno-tab>
 </deno-tabs>
 
-| Field      | Required | Details                                                                                                                    |
-| ---------- | -------- | -------------------------------------------------------------------------------------------------------------------------- |
-| `slug`     | ✅       | Unique per organization. Slugs become part of the mount metadata, so pick something descriptive.                           |
-| `region`   | ✅       | Must match an available sandbox region (`"ord"` or `"ams"` today). Only sandboxes in the same region can mount the volume. |
-| `capacity` | ✅       | Between 300 MB and 20 GB. Pass a number of bytes or a string with `GB/MB/KB` (decimal) or `GiB/MiB/KiB` (binary) units.    |
+| Field      | Required | Details                                                                                                                 |
+| ---------- | -------- | ----------------------------------------------------------------------------------------------------------------------- |
+| `slug`     | ✅       | Unique per organization. Slugs become part of the mount metadata, so pick something descriptive.                        |
+| `region`   | ✅       | Currently only `"ord"` (Chicago) is supported. Only sandboxes in the same region can mount the volume.                  |
+| `capacity` | ✅       | Between 300 MB and 20 GB. Pass a number of bytes or a string with `GB/MB/KB` (decimal) or `GiB/MiB/KiB` (binary) units. |
 
 ### Inspect and search volumes