message: Fix Unescape backslash in default envs
diff: {
  "document": {
  - "snippet": "\\n$0"
  + "snippet": "\n$0"
  },
  "table": {},
  "description": {
  - "snippet": "\\n\\t\\\\item[$1] $0"
  + "snippet": "\n\t\\item[$1] $0"
  },
  "enumerate": {
  - "snippet": "\\n\\t\\\\item $0"
  + "snippet": "\n\t\\item $0"
  },
  "itemize": {
  - "snippet": "\\n\\t\\\\item $0"
  + "snippet": "\n\t\\item $0"
  },
  "math": {},
  "displaymath": {},
  