[folding] Folded regions are lost when starting multi line comment Fixes Microsoft/vscode#46655

extensions/html/language-configuration.json

@@ -13,7 +13,8 @@
 		{ "open": "[", "close": "]"},
 		{ "open": "(", "close": ")" },
 		{ "open": "'", "close": "'" },
-		{ "open": "\"", "close": "\"" }
+		{ "open": "\"", "close": "\"" },
+		{ "open": "<!--", "close": "-->", "notIn": [ "comment", "string" ]}
 	],
 	"surroundingPairs": [
 		{ "open": "'", "close": "'" },