osbuilder: Document no Alpine support on s390x
Alpine used to work as guest under 1.x, but because there is no musl
target for Rust on s390x, Alpine will not work for 2.x. Document this.
Fixes:
@@ -213,5 +213,5 @@ any Linux distribution and architecture where dracut is available.
|-- |-- |-- |-- |-- |-- |-- |
|**ARM64** |:heavy_check_mark:|:heavy_check_mark:| | |:heavy_check_mark:|:heavy_check_mark:|
|**PPC64le**|:heavy_check_mark:|:heavy_check_mark:| |:heavy_check_mark:|:heavy_check_mark:|:heavy_check_mark:|
-|**s390x** |:heavy_check_mark:| | |:heavy_check_mark:|:heavy_check_mark:| |
+|**s390x** | | | |:heavy_check_mark:|:heavy_check_mark:| |
|**x86_64** |:heavy_check_mark:|:heavy_check_mark:|:heavy_check_mark:|:heavy_check_mark:|:heavy_check_mark:|:heavy_check_mark:|
