docs: clarify backend selection, Fly.io costs, and Object Storage request scaling

docs/setup_flyio.md

@@ -3,16 +3,30 @@
 
 This is how to configure fly.io and CouchDB on it for Self-hosted LiveSync.
 
-The CouchDB instance is yours to manage. You can configure it yourself or set up another instance and switch to it, following the preservation and recovery guidance below.
+The CouchDB instance is yours to manage, including its updates, credentials, and backups.
+
+This guide prepares hosted CouchDB, then leads to [first-device setup](quick_setup.md#configure-couchdb-manually-on-the-first-device), [a Setup URI from that working device](quick_setup.md#create-a-setup-uri-for-another-device), and [additional-device setup with a two-way check](quick_setup.md#add-another-device). Review the costs below before deploying an application.
+
+## Costs before deployment
+
+Fly.io provides cloud infrastructure on which you run your own CouchDB container. A valid credit or debit card is required upon registration. A time-limited trial or sign-up credit does not provide ongoing free hosting.
+
+As a general cost illustration, based on [Fly.io pricing](https://fly.io/pricing/) (reviewed late 2026), a minimal configuration typically costs around **USD 2.00–3.00 per month**:
+
+| Resource | Basis of calculation | Approximate monthly cost |
+| --- | --- | --- |
+| One `shared-cpu-1x` Machine (256 MB RAM) | Running continuously (~730 hours @ ~USD 0.0030/hr) | ~USD 2.19 |
+| One 1 GB persistent volume | Provisioned storage (~USD 0.15/GB-month) | ~USD 0.15 |
+| **Estimated subtotal** | Compute and persistent storage | **~USD 2.34 / month** |
+
+*Note: Rates vary depending on the chosen Fly.io region, outbound network bandwidth, and optional dedicated IP addresses. The template configuration enables automatic machine suspension (`auto_stop_machines = true`), which may reduce running hours and compute costs when synchronisation is idle, though provisioned storage volumes continue to be billed.*
 
 > [!WARNING]
 > Before replacing or deleting an existing CouchDB instance, back up every available Vault and the remote database, then [choose the authoritative copy](recovery.md#first-choose-the-authoritative-copy). Stop or suspend synchronisation on other devices while reviewing recovery options. Local files alone do not establish that every needed edit or revision has been preserved.
 
 > [!NOTE] 
 > **What and why is the Fly.io?**  
-> At some point, we started to experience problems related to our IBM Cloudant account. At the same time, Self-hosted LiveSync started to improve its functionality, requiring CouchDB in a more natural state to use all its features.
->
-> Fly.io charges according to current account and resource usage, including Machines, persistent volumes, and network usage. Check [Fly.io pricing](https://fly.io/pricing/) and the [pricing documentation](https://fly.io/docs/about/pricing/) before deploying. A time-limited trial does not provide ongoing free hosting.
+> Fly.io hosts the Machine and persistent volume while you administer CouchDB. For other environments, see [your own server](setup_own_server.md), the [Docker stack](../docker/README.md), or [IBM Cloudant](setup_cloudant.md).
 
 ## Required materials
 
@@ -267,8 +281,16 @@ Note: Each of these should also be repeated until finished in 200.
 
 #### 6. Use it from Self-hosted LiveSync
 
-Now the CouchDB is ready to use from Self-hosted LiveSync. Use your Fly.io app's hostname in `URI`, and the unique credentials configured above in `Username` and `Password`. The `Database name` could be anything you want.
-Please refer to [Configure CouchDB manually on the first device](./quick_setup.md#configure-couchdb-manually-on-the-first-device).
+Now CouchDB is ready for Self-hosted LiveSync. Use these values during manual setup:
+
+| Prepared value | Setup dialogue field |
+| --- | --- |
+| `https://<your-app>.fly.dev` | `URL` |
+| Your configured `COUCHDB_USER` | `Username` |
+| Your configured `COUCHDB_PASSWORD` secret | `Password` |
+| Your chosen database name, such as `obsidiannotes` | `Database Name` |
+
+Please refer to [Configure CouchDB manually on the first device](./quick_setup.md#configure-couchdb-manually-on-the-first-device). After your first device synchronises a test note, generate a new Setup URI on that device and follow the additional-device steps in Quick setup. Confirm that a note created on each device reaches the other unchanged.
 
 ## Delete the Instance