WebAssemblyMCTargetDesc.cpp: fix a typo in a description

Author: yamt

llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyMCTargetDesc.cpp

@@ -56,7 +56,7 @@ cl::opt<bool> WebAssembly::WasmEnableSjLj(
     "wasm-enable-sjlj", cl::desc("WebAssembly setjmp/longjmp handling"));
 cl::opt<bool> WebAssembly::WasmEnableAltSjLj(
     "experimental-wasm-enable-alt-sjlj",
-    cl::desc("Use experimental alternate ABI for --wasm-enable-sjlj"));
+    cl::desc("Use experimental alternate ABI for -wasm-enable-sjlj"));
 
 static MCAsmInfo *createMCAsmInfo(const MCRegisterInfo & /*MRI*/,
                                   const Triple &TT,