chore(sfc-playground): add README to link to its website (vuejs#6346) [ci skip]

CHOYSEN · zhangzhonghe · commit 04e2beafcd29 · 2023-04-12T09:26:32.000+08:00
diff --git a/packages/sfc-playground/README.md b/packages/sfc-playground/README.md
@@ -0,0 +1,3 @@
+## SFC Playground
+
+This is continuously deployed at [https://sfc.vuejs.org](https://sfc.vuejs.org).

Original file line number	Diff line number	Diff line change
`@@ -0,0 +1,3 @@`
	`1`	`+## SFC Playground`
	`2`	`+`
	`3`	`+This is continuously deployed at [https://sfc.vuejs.org](https://sfc.vuejs.org).`