docs(site-to-vpn): rename target peer to overlay-peer / overlay-peers

The previous backup-collector / backup-collectors naming carried
scenario-specific framing into the step examples. Use the generic
overlay-peer / overlay-peers throughout to keep the guide universal.

src/pages/manage/networks/use-cases/site-to-vpn.mdx

@@ -49,7 +49,7 @@ access control. See [Outbound SNAT requirement](#outbound-snat-requirement).
 - **Routing peer (`site-router`):** site IP `192.168.50.10`, NetBird IP
   assigned at enrollment
 - **Clientless device:** `192.168.50.20`
-- **Target NetBird peer (`backup-collector`):** runs the NetBird client; we
+- **Target NetBird peer (`overlay-peer`):** runs the NetBird client; we
   reach it on TCP port `8080`
 
 ## Step 1: Create Setup Keys with Groups
@@ -67,7 +67,7 @@ auto-assigned group so the peer lands in the right place:
 The target peer is a regular NetBird peer; nothing special needs to be
 configured on it for this scenario. If the target peer is a service or
 appliance (not a user device), create a second setup key for it the same
-way and add it to a group like `backup-collectors`. User peers — laptops
+way and add it to a group like `overlay-peers`. User peers — laptops
 and workstations — enroll through SSO instead and pick up their group via
 your existing group assignments.
 
@@ -158,11 +158,11 @@ NetBird IP, the policy uses peer groups:
 
 1. Go to **Access Control** → **Policies** and click **Add Policy**
 2. Configure:
-   - **Name:** `Site Router to Backup Collector`
+   - **Name:** `Site Router to Overlay Peer`
    - **Protocol:** `TCP`
    - **Ports:** `8080` (or `All` to allow any port)
    - **Source Groups:** `site-routing-peers`
-   - **Destination Groups:** `backup-collectors`
+   - **Destination Groups:** `overlay-peers`
 3. Click **Add Policy**
 
 ## Step 6: Direct Site Traffic Through the Routing Peer
@@ -269,7 +269,7 @@ Then point the clientless device's DNS at `192.168.50.10` (via DHCP,
 directly:
 
 ```bash
-curl http://backup-collector.netbird.cloud:8080/
+curl http://overlay-peer.netbird.cloud:8080/
 ```
 
 <Note>