Redirects users to tested example (#791)

Rather than clutter both the README and home page with details that can
drift and have caused maintenance, this directs users to the tested
basic example.

This also adds a FAQ entry about TinyGo's main, thanks to @basvanbeek
for the help.

Signed-off-by: Adrian Cole <adrian@tetrate.io>

example_test.go

@@ -1,48 +1,62 @@
-package wazero
+package wazero_test
 
 import (
 	"context"
 	_ "embed"
 	"fmt"
 	"log"
+
+	"github.com/tetratelabs/wazero"
+	"github.com/tetratelabs/wazero/imports/wasi_snapshot_preview1"
 )
 
 // addWasm was generated by the following:
 //
-//	cd examples/basic/testdata/testdata; wat2wasm --debug-names add.wat
+//	cd examples/basic/testdata; tinygo build -o add.wasm -target=wasi add.go
 //
 //go:embed examples/basic/testdata/add.wasm
 var addWasm []byte
 
-// This is an example of how to use WebAssembly via adding two numbers.
+// This is an example of how to extend a Go application with an addition
+// function defined in WebAssembly.
 //
-// See https://github.com/tetratelabs/wazero/tree/main/examples for more.
+// Since addWasm was compiled with TinyGo's `wasi` target, we need to configure
+// WASI host imports.
+//
+// A complete project that does the same as this is available here:
+// https://github.com/tetratelabs/wazero/tree/main/examples/basic
 func Example() {
 	// Choose the context to use for function calls.
 	ctx := context.Background()
 
 	// Create a new WebAssembly Runtime.
-	r := NewRuntime(ctx)
+	r := wazero.NewRuntimeWithConfig(ctx, wazero.NewRuntimeConfig().
+		// WebAssembly 2.0 allows use of any version of TinyGo, including 0.24+.
+		WithWasmCore2())
+	defer r.Close(ctx) // This closes everything this Runtime created.
 
-	// Add a module to the runtime named "wasm/math" which exports one function
-	// "add", implemented in WebAssembly.
+	// Instantiate WASI, which implements host functions needed for TinyGo to
+	// implement `panic`.
+	if _, err := wasi_snapshot_preview1.Instantiate(ctx, r); err != nil {
+		log.Panicln(err)
+	}
+
+	// Instantiate the guest Wasm into the same runtime. It exports the `add`
+	// function, implemented in WebAssembly.
 	mod, err := r.InstantiateModuleFromBinary(ctx, addWasm)
 	if err != nil {
 		log.Panicln(err)
 	}
-	defer mod.Close(ctx)
-
-	// Get a function that can be reused until its module is closed:
-	add := mod.ExportedFunction("add")
 
+	// Call the `add` function and print the results to the console.
 	x, y := uint64(1), uint64(2)
-	results, err := add.Call(ctx, x, y)
+	results, err := mod.ExportedFunction("add").Call(ctx, x, y)
 	if err != nil {
 		log.Panicln(err)
 	}
 
-	fmt.Printf("%s: %d + %d = %d\n", mod.Name(), x, y, results[0])
+	fmt.Printf("%d + %d = %d\n", x, y, results[0])
 
 	// Output:
-	// wasm/math: 1 + 2 = 3
+	// 1 + 2 = 3
 }