end region marker for html/xml should be #endregion

[eiswind]

the endregion marker in the regex for html/xml is #region

https://github.com/slidevjs/slidev/blob/ba6a0047dff59f431d994441dee15e80578b2ba7/packages/slidev/node/syntax/transform/snippet.ts#L36

i think it should be #endregion, at least this is what vscode expects.