Remove definition list snippet

#134611

This is non-standard md and was incorrectly added. Instead the snippet should be included by whatever extension introduces support for this syntax

extensions/markdown-basics/snippets/markdown.code-snippets

@@ -64,11 +64,6 @@
 		"body": ["1. ${1:first}", "2. ${2:second}", "3. ${3:third}", "$0"],
 		"description": "Insert ordered list"
 	},
-	"Insert definition list": {
-	        "prefix": "definition list",
-		"body": ["${1:term}", ": ${2:definition}", "$0"],
-		"description": "Insert definition list"
-	},
 	"Insert horizontal rule": {
 		"prefix": "horizontal rule",
 		"body": "----------\n",