[docs] Add more self-hosting instructions (#996)

- How to set custom server
- How to build for mobile

/ping @ua741 @vishnukvmd

docs/docs/.vitepress/sidebar.ts

@@ -84,6 +84,8 @@ export const sidebar = [
                 text: "Guides",
                 items: [
                     { text: "Introduction", link: "/self-hosting/guides/" },
+                    { text: "Configure custom server", link: "/self-hosting/guides/custom-server/" },
+                    { text: "Mobile build", link: "/self-hosting/guides/mobile-build" },
                     {
                         text: "System requirements",
                         link: "/self-hosting/guides/system-requirements",

docs/docs/self-hosting/guides/custom-server/index.md

@@ -0,0 +1,19 @@
+---
+title: Custom server
+description: Using a custom self-hosted server with frontend apps
+---
+
+# Custom server for mobile apps
+
+The pre-built Ente apps from GitHub / App Store / Play Store / F-Droid can be
+easily configured to use a custom server.
+
+You can tap 7 times on the onboarding screen to bring up a page where you can
+configure the endpoint the app should be connecting to.
+
+![Setting a custom server on the onboarding screen](custom-server.png)
+
+> [!IMPORTANT]
+>
+> This is only supported by the Ente Auth app currently. We'll add this same
+> functionality to the Ente Photos app soon.

docs/docs/self-hosting/guides/mobile-build.md

@@ -0,0 +1,35 @@
+---
+title: Building mobile apps
+description: Connecting to your custom self-hosted server when building the Ente mobile apps from source
+---
+
+# Mobile: Build and connect to self-hosted server
+
+The up to date instructions to build the mobile apps are in the [Ente
+Photos](https://github.com/ente-io/ente/tree/main/mobile#readme) and [Ente
+Auth](https://github.com/ente-io/ente/tree/main/auth#readme) READMEs. When
+building or running, you can use the
+
+```sh
+--dart-define=endpoint=http://localhost:8080
+```
+
+parameter to get these builds to connect to your custom self-hosted server.
+
+As a short summary, you can install Flutter and build the Photos app this way:
+
+```sh
+cd ente/mobile
+git submodule update --init --recursive
+flutter pub get
+flutter run --dart-define=endpoint=http://localhost:8080
+```
+
+Or for the auth app:
+
+```sh
+cd ente/auth
+git submodule update --init --recursive
+flutter pub get
+flutter run --dart-define=endpoint=http://localhost:8080
+```

docs/docs/self-hosting/index.md

@@ -38,6 +38,13 @@ an account on a Ente Photos web app running on your machine, and this web app
 will be connecting to the server running on your local machine at
 localhost:8080.
 
+For the mobile apps, you don't even need to build, and can install normal Ente
+apps and configure them to use your [custom self-hosted
+server](guides/custom-server).
+
+> If you want to build from source, see the instructions
+[here](guides/mobile-build).
+
 ## Next steps
 
 * More details about the server are in its