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>

examples/basic/testdata/add.go

@@ -0,0 +1,10 @@
+package main
+
+//export add
+func add(x, y uint32) uint32 {
+	return x + y
+}
+
+// main is required for the `wasi` target, even if it isn't used.
+// See https://wazero.io/languages/tinygo/#why-do-i-have-to-define-main
+func main() {}

examples/basic/testdata/add.wat

@@ -1,15 +0,0 @@
-(module
-  ;; Define the optional module name. '$' prefixing is a part of the text format.
-  $wasm/math
-
-  ;; add returns $x+$y.
-  ;;
-  ;; Notes:
-  ;; * The stack begins empty and anything left must match the result type.
-  ;; * export allows api.Module to return this via ExportedFunction("add")
-  (func (export "add") (param $x i32) (param $y i32) (result i32)
-    local.get $x ;; stack: [$x]
-    local.get $y ;; stack: [$x, $y]
-    i32.add      ;; stack: [$x+$y]
-  )
-)