Update R8/ProGuard section of README.md

[connyduck]

closes #572

[Unpublished]

I don't have a strong opinion on this.

I think some breakages in downstream apps caused by obfuscation could be fixed in this library. But would require a lot effort/time to narrow down.

Thats why I personally wouldn't advertise using "will automatically work without additional app level rules".

This is partially covered with line 286, though.

[connyduck]

Are there known breakages in downstream apps? For the two apps I worked with it was fine.

[Unpublished]

The news app had crashes related to sso with obfuscation enabled last time I tested.

In case you try to reproduce:
I removed too broad rules like "keep all classes in all nextcloud news packages"

[connyduck]

I built the news-android app without -dontobfuscate. The resulting apk is about 7% smaller (4965kB vs 5319kB) and works just fine (as far as I can tell with my Nextcloud setup). I don't see any rules I'd call too broad.

[Unpublished]

I'd call -keep class de.luhmer.** { *; } too broad. But if it works now, fine 👍

[connyduck]

Oh that are the application classes, I was looking for com.nextcloud, my bad. Here is a suggestion to improve the situation:
nextcloud/news-android#1382

[Unpublished]

Since there are no known broken downstream apps anymore this can be merged