Echo JS 0.11.0

Love the series. I would mention the `readonly` and `as const` expressions for TypeScript tuples. `readonly` is necessary to make tuples immutable in TypeScript. `as const` allows you to easily create immutable tuples without repeating yourself. Example in playground:

https://www.typescriptlang.org/play?#code/FAb2AJwMwVwOwMYBcCWB7O4DmBTJBhNNAJwBMU4BDJHAZwAoBKALnGJ0tIwBsBPcANpwYAWwBGOYgBpww8ZJlyJxALrgwkSAgy0k4AB7gAvOACMAbgibtcXeH4mATJc3gbdgF7HwAZktXIdiQYYkwBfRleGQ8VF3AAX2Ardz0ABzQKPRNcAiIyCmo6JiTIAHpS8HxKODg0PUpaWhQsTCQ0cAByAAYO8AkEShhaHHAUPRRacEo2DlIAWh5+VOI0VMkkXgA6ekcAVgAWLsYrdMyBLrUTAE4S8HLwABUYVO4RjbXO9k5FwSUFWVEykUgMkKl6aCg4FecCwSAAFp0fL04Q1ZO0cK8RDg4PVxnBSDhDB0kZtkjo9AIAO4yCL2aKXbB4QgkchUGgMRj+RKgKz3ACqTRh4AABqiUsLwBhwPCRkEQpgAG6UbgwEZUYgrSmTGXS9rTd4jbhjSTK2hWWCIVBSnLM-JsoqMdQBNzkgzeCzOlL2bzOT2urwmPy3QJ4eWCWlRcAxKaTFJxRKQMm2NIZHHeG15VmFDl3CoUKCSdikaW8NasL5cOB8QSmGSOGQ+FS3U4484Mq6uTtd7td+6AXg3ALI74F0KG43CmmELJCTdipNMi9PTTMzBXZTHMZQqg+HqDHE-AU+It3unHIVqoY-4BJoyEm6UaKDEr1GjVVk0pYwR2hEqUoxAmOi6lCxrEMq4BKiqdDMFYKCQvQLZIG2xhGNcjogPEuaPHCEwuj+f4AZglCpGsf7au0EjgPAmTYueYH9IMwzSnCbylnQnSmL01TFh0VzIpQCpqu0aACcQ3BEaS3IaJhDysQAygg-6pHolIYB0ejqpqB76MsdBNIB9A4JsWCbDIwqYAA1GYwosOa8DIOgmAZiyq5FJgJimGhfrJm67lxForoOLI4CWR6rhegGQWWb6zpyqE4YLlGahiuS8a3F6CFLrkzn2gwuyOvc+aFjgxYGuWsw-AItYAvI0jVcoTYnKmiEXN4HY9u1HX9kOI57tUB4atO-neXOBgJdG2TLtl2brpu4Dbj1459VYvIVAt4DXjgt7gMsaBPjgIjgJSzGYN+v7-kKCFtjIYgwOpdTbU1lVNpAsHgPBj0tShqHqBh9wPNhsZoHh-60FKREkcQZF9CMVE4jRDl0ZtDFvMxJZrJMHQcRO3G8eAKICWikoiWJqSki9cGXaYlwoeAVxob9FS1P1KxHpJK1YSMIhoHYQw4LA44DIxUAkCKyXJhKOFHdibhfKgQrBC8hogaa0FDXYGUmJVdYNklgPeQVcAFhqxVozgZXfFW-Ba+A9a+A1kCXZ9tMdd2XU7qOi2TgNR5qxS1KjXSiXeAhG6YfNu6e+Ay2zWtG1bTte0HVLJ1A2dFBYA9ZwXNdt1oimZxUzBFMfdT33odJAO4WnoOEcRHCQ0BFGwzQOII+O9G80xLHo+xnH4p0uP44JROSCTZOjMXBel7T9OYaa7RQGJWC4KQwDxEAA