src/examples/wasm: Show both methods supported

Adds another example showing the simple case
of executing main, adds a README explaining how
everything fits together and how to execute the compiled
code in the browser. Include a minimal webserver for
local testing.

src/examples/wasm/Makefile

@@ -0,0 +1,15 @@
+export: clean wasm_exec
+	tinygo build -o ./html/wasm.wasm -target wasm ./export/wasm.go
+	cp ./export/wasm.js ./html/
+	cp ./export/index.html ./html/
+
+main: clean wasm_exec
+	tinygo build -o ./html/wasm.wasm -target wasm ./main/main.go
+	cp ./main/index.html ./html/
+
+wasm_exec:
+	cp ../../../targets/wasm_exec.js ./html/
+
+clean:
+	rm -rf ./html
+	mkdir ./html