Remove stale iOS 15 notes; state iOS 17.6 minimum for watch users (#1072)

The Apple Watch section of the build page still said the minimum iOS is
15.1 (watchOS 8.1), contradicting the iOS 17.6 / watchOS 10.6 minimum
stated on the phone and watch pages since v3.14.7. Also drop the iOS 15
Developer Mode and German-language notes, since iOS 15 is no longer
supported.

Author: ps2

docs/build/build-app.md

@@ -28,11 +28,7 @@ If you previously used [Build with Browser](../browser/bb-overview.md) to instal
 
 ## <code>Developer Mode</code>
 
-If you are running iOS 15/watchOS 8, you do not have <code>Developer Mode</code> and can skip ahead to [Download Loop](#download-loop).
-
-### Upgrade from iOS 15 to newer version
-
-**If you upgrade an iOS 15 phone to iOS 16 or newer, the *Loop* app will not open until you enable <code>Developer Mode</code> on that phone.**
+**If <code>Developer Mode</code> is not enabled, the *Loop* app built with Xcode will not open on that phone.**
 
 You will see a message similar to the next graphic.
 
@@ -524,7 +520,7 @@ To add custom configurations to your Loop or Loop Apple Watch apps, follow the s
 
 ### Apple Watch
 
-**Existing Apple Watch users**: Please update your watchOS prior to building the Loop app. The minimum iOS for Loop 3 is iOS 15.1, which means watchOS 8.1. When running iOS 16.x, you will need a watchOS of 9.x.
+**Existing Apple Watch users**: Please update your watchOS prior to building the Loop app. The minimum iOS for the *Loop* app is iOS 17.6, which means watchOS 10.6. See [Watch Hardware and OS Requirements](../operation/features/watch.md#watch-hardware-and-os-requirements){: target="_blank" }.
 
 **New Apple Watch users**: If you have an Apple watch and want to use it with Loop, first pair the watch with the iPhone before continuing to the next steps.  If you get a new watch after building the Loop app, you'll need to redo your Loop build.
 

docs/loop-3/settings.md

@@ -123,9 +123,6 @@ If you want to use Loop in parallel with your current method of dosing insulin.
 
 ### Usage Data Sharing
 
-!!! warning "iOS 15"
-    If you are running an iOS 15 device, this screen is shown in German regardless of the language you choose for Loop. That is an accident that will be fixed by the next release. The English version is shown below.
-
 You can review and modify your preference for Usage Data Sharing as shown in the graphic below:
 
 ![review or modify usage data sharing with Loop developers](img/data-sharing-revisit.svg){width="350"}