fix: remove colon from title to appease build (#2012)

Co-authored-by: Injoong Yoon <[email protected]>

Author: injoongy

machines/guides-examples/one-app-per-user-why.html.markerb

@@ -1,5 +1,5 @@
 ---
-title: One app per customer: why?
+title: One app per customer - why?
 layout: docs
 order: 15
 nav: machines
@@ -28,4 +28,4 @@ The [Custom private networks](https://fly.io/docs/networking/custom-private-netw
 
 * Application A (non-isolated) can have a `.flycast` IP address in application B’s (isolated) subnet, so they can talk to each other over that IP address. You can do this using `fly ips allocate-v6 --private -a APP_A --network APP_B_NETWORK`. App A can then contact “app-b.flycast” directly.
 * Using the [fly-replay header](https://fly.io/docs/networking/dynamic-request-routing/), an application can direct requests to machines in another application, even if that one resides on a private subnet.
-* If application B (isolated) exposes a public service, then other applications (isolated or not) can access it over the Internet using its public name.
+* If application B (isolated) exposes a public service, then other applications (isolated or not) can access it over the Internet using its public name.