Update index.html

Author: aquynh

index.html

@@ -8,7 +8,7 @@
 Highlight features:
 
 <ul>
-<li>Multi-architectures: ARM, ARM64 (ARMv8), m68k, MIPS, PowerPC, RISC-V, SPARC, & x86 (include x86_64).</li>
+<li>Multi-architectures: ARM, ARM64 (ARMv8), m68k, MIPS, PowerPC, RISC-V, S390x (SystemZ), SPARC, & x86 (include x86_64).</li>
 
 <li>Clean/simple/lightweight/intuitive architecture-neutral API.</li>