[NFC] Improve wasm-opt help text (#7631)

Add an example + wiki links.

Author: kripken

src/tools/wasm-opt.cpp

@@ -95,7 +95,21 @@ int main(int argc, const char* argv[]) {
 
   const std::string WasmOptOption = "wasm-opt options";
 
-  OptimizationOptions options("wasm-opt", "Read, write, and optimize files");
+  OptimizationOptions options("wasm-opt",
+                              R"(Read, write, and optimize files.
+
+Example usage:
+
+  wasm-opt input.wasm -O3 -o output.wasm
+
+This reads an input wasm file, optimizes with -O3, and writes out the result.
+
+For more on how to optimize effectively, see
+
+  https://github.com/WebAssembly/binaryen/wiki/Optimizer-Cookbook
+  https://github.com/WebAssembly/binaryen/wiki/GC-Optimization-Guidebook
+                            )");
+
   options
     .add("--output",
          "-o",

test/lit/help/wasm-opt.test

@@ -2,7 +2,19 @@
 ;; CHECK: ================================================================================
 ;; CHECK-NEXT: wasm-opt INFILE
 ;; CHECK-NEXT:
-;; CHECK-NEXT: Read, write, and optimize files
+;; CHECK-NEXT: Read, write, and optimize files.
+;; CHECK-NEXT:
+;; CHECK-NEXT: Example usage:
+;; CHECK-NEXT:
+;; CHECK-NEXT:   wasm-opt input.wasm -O3 -o output.wasm
+;; CHECK-NEXT:
+;; CHECK-NEXT: This reads an input wasm file, optimizes with -O3, and writes out the result.
+;; CHECK-NEXT:
+;; CHECK-NEXT: For more on how to optimize effectively, see
+;; CHECK-NEXT:
+;; CHECK-NEXT:   https://github.com/WebAssembly/binaryen/wiki/Optimizer-Cookbook
+;; CHECK-NEXT:   https://github.com/WebAssembly/binaryen/wiki/GC-Optimization-Guidebook
+;; CHECK-NEXT:
 ;; CHECK-NEXT: ================================================================================
 ;; CHECK-NEXT:
 ;; CHECK-NEXT: