[Cloudflare One] Revert tunnel capitalization to lowercase

Refers to the tunnel instance, not the Cloudflare Tunnel product name.
Reverts to match production.

Author: codyanthony850

src/content/docs/cloudflare-one/setup/replace-vpn/device-to-network.mdx

@@ -42,7 +42,7 @@ Cloudflare Tunnel establishes an outbound connection between your resources and
 
 ## Step 2: Set your Tunnel's IP range
 
-Add the IP range of your private network to the Tunnel. This defines which internal resources your remote users can reach. Your Tunnel accepts traffic to this range from devices enrolled in your Zero Trust organization.
+Add the IP range of your private network to the tunnel. This defines which internal resources your remote users can reach. Your tunnel accepts traffic to this range from devices enrolled in your Zero Trust organization.
 
 1. Enter your IP range (for example, `10.0.1.0/24`).
 2. Select **Continue**.