Include support for ZSTD compressed file systems

configname: CONFIG_SQUASHFS_ZSTD

Linux Kernel Configuration
└─>File systems
└─>Miscellaneous filesystems
└─>Include support for ZSTD compressed file systems
In linux kernel since version 4.2 (release Date: 2015-08-30)  
Saying Y here includes support for reading Squashfs file systems
compressed with ZSTD compression. ZSTD gives better compression than
the default ZLIB compression, while using less CPU.

ZSTD is not the standard compression used in Squashfs and so most
file systems will be readable without selecting this option.

If unsure, say N.