Revert "README.me: disable riscv64"

This reverts commit 80dc048.

README.md

@@ -88,14 +88,12 @@ It includes
 |Ubuntu/arm64            |Yes (on qemu)    |                             |
 |Ubuntu/armhf            |Yes (on qemu)    |32-bit                       |
 |Ubuntu/s390x            |Yes (on qemu)    |Big endian                   |
-|Ubuntu/riscv64          |Yes (on qemu)    |[Temporarily disabled]       |
+|Ubuntu/riscv64          |Yes (on qemu)    |                             |
 |wasm32-wasi-threads     |No               |Occasionally tested manually |
 |NuttX/esp32             |No               |Occasionally tested manually |
 |NuttX/sim on macOS/amd64|No               |Occasionally tested manually |
 |NetBSD/amd64            |No               |Occasionally tested manually |
 
-[Temporarily disabled]: https://github.com/yamt/toywasm/issues/80
-
 ## Use as a command
 
 See [toywasm command help message](https://webassembly.sh/?run-command=toywasm).