Q152- explanation is wrong

The answer states that:
```
The Promise.all method runs the passed promises in parallel
```
There is no such concept as parallelism in JavaScript as it is single-threaded. [MDN docs](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise#promise_concurrency) also suggests the name concurrency for these methods.

I'll be happy to do a PR.