Fix in-page anchor link on exoplayer.dev troubleshooting page

Also consolidate the threading warning info with the same info on the
hello world page and update the version that the
setThrowsWhenUsingWrongThread() method will be removed in.

PiperOrigin-RevId: 369657759

docs/hello-world.md

@@ -132,7 +132,7 @@ shows you where). You can temporarily opt out from these exceptions being thrown
 by calling `SimpleExoPlayer.setThrowsWhenUsingWrongThread(false)`, in which case
 the issue will be logged as a warning instead. Using this opt out is not safe
 and may result in unexpected or obscure errors. It will be removed in ExoPlayer
-2.14.
+2.16.
 {:.info}
 
 For more information about ExoPlayer's treading model, see the

docs/troubleshooting.md

@@ -14,7 +14,7 @@ redirect_from:
 * [Why do some streams fail with HTTP response code 301 or 302?][]
 * [Why do some streams fail with UnrecognizedInputFormatException?][]
 * [Why doesn't setPlaybackParameters work properly on some devices?][]
-* [What do "Player is accessed on the wrong thread" warnings mean?][]
+* [What do "Player is accessed on the wrong thread" errors mean?][]
 * [How can I fix "Unexpected status line: ICY 200 OK"?][]
 * [How can I query whether the stream being played is a live stream?][]
 * [How do I keep audio playing when my app is backgrounded?][]
@@ -204,17 +204,7 @@ releases you provide to end users should not be affected by this issue.
 
 #### What do "Player is accessed on the wrong thread" errors mean? ####
 
-If you are seeing `IllegalStateException` being thrown with the message "Player
-is accessed on the wrong thread", then some code in your app is accessing a
-`SimpleExoPlayer` instance on the wrong thread (the exception's stack trace
-shows you where). ExoPlayer instances need to be accessed from a single thread
-only. In most cases, this should be the application's main thread. For details,
-please read through the ["Threading model" section of the ExoPlayer Javadoc][].
-You can temporarily opt out from these exceptions being thrown by calling
-`SimpleExoPlayer.setThrowsWhenUsingWrongThread(false)`, in which case the issue
-will be logged as a warning instead. Using this opt out is not safe and may
-result in unexpected or obscure errors. The opt out will be removed in ExoPlayer
-2.14.
+See [A note on threading][] on the getting started page.
 
 #### How can I fix "Unexpected status line: ICY 200 OK"? ####
 
@@ -313,7 +303,7 @@ is the official way to play YouTube videos on Android.
 [Why do some streams fail with HTTP response code 301 or 302?]: #why-do-some-streams-fail-with-http-response-code-301-or-302
 [Why do some streams fail with UnrecognizedInputFormatException?]: #why-do-some-streams-fail-with-unrecognizedinputformatexception
 [Why doesn't setPlaybackParameters work properly on some devices?]: #why-doesnt-setplaybackparameters-work-properly-on-some-devices
-[What do "Player is accessed on the wrong thread" warnings mean?]: #what-do-player-is-accessed-on-the-wrong-thread-warnings-mean
+[What do "Player is accessed on the wrong thread" errors mean?]: #what-do-player-is-accessed-on-the-wrong-thread-errors-mean
 [How can I fix "Unexpected status line: ICY 200 OK"?]:  #how-can-i-fix-unexpected-status-line-icy-200-ok
 [How can I query whether the stream being played is a live stream?]: #how-can-i-query-whether-the-stream-being-played-is-a-live-stream
 [How do I keep audio playing when my app is backgrounded?]: #how-do-i-keep-audio-playing-when-my-app-is-backgrounded
@@ -347,7 +337,7 @@ is the official way to play YouTube videos on Android.
 [`WakeLock`]: {{ site.android_sdk }}/android/os/PowerManager.WakeLock.html
 [`SimpleExoPlayer`]: {{ site.exo_sdk }}/SimpleExoPlayer.html
 [`setWakeMode`]: {{ site.exo_sdk }}/SimpleExoPlayer.html#setWakeMode-int-
-["Threading model" section of the ExoPlayer Javadoc]: {{ site.exo_sdk }}/ExoPlayer.html
+[A note on threading]: {{ site.base_url }}/hello-world.html#a-note-on-threading
 [OkHttp extension]: {{ site.release_v2 }}/extensions/okhttp
 [CORS enabled]: https://www.w3.org/wiki/CORS_Enabled
 [Cast framework]: {{ site.google_sdk }}/cast/docs/chrome_sender/advanced#cors_requirements