docs: link AltStore distribution

.gitignore

@@ -2,3 +2,4 @@
 .env
 xcuserdata/
 *.xcuserstate
+/distribution/

README.md

@@ -127,6 +127,10 @@ sharing, notifications, and background refresh.
 
 ## iOS app
 
+Prebuilt iPhone releases will be distributed through the
+[rfc1437 Apps AltStore PAL source](https://rfc1437.de/apps/). The source page
+explains how to add it to AltStore PAL and install available apps.
+
 Server tokens are kept in the Apple Keychain; JSON preferences contain only
 server metadata, settings, and favorites. The app requires Xcode, XcodeGen, an
 installed iOS Simulator runtime, and Rust's