[DOC release] Change misleading documentation for AdapterPopulatedRecordArray

[happycollision]

In my experimentation, I've discovered that though the promise returned from store.query() does have array-like methods on it, the actual AdapterPopulatedRecordArray is what the promise resolves to. The promise does not behave like a proxy (or what I think Ember Proxies do...). The documentation for store.query states this plainly, but the documentation here misrepresented that.

For example, the original code actually would behave like this:

  // GET /users?isAdmin=true
  var admins = store.query('user', { isAdmin: true });

  admins.then(function() {
    console.log(admins.get("length")); // Throws: "admins.get" is not a function
  });

[happycollision]

I'm about to force push to change the commit message to meet your standards.

[happycollision]

And once more to remove things inside the commit message where I am speaking a little bit about things I don't know.

I realize that when I read commit messages that are merged, I take them to be the actual truth. In my original commit message, I made a comment referring to Ember's ProxyObjects, but I am really not 100% sure how those work. And that comment is actually not pertinent to this change anyhow.

[runspired]

I'm in favor of this documentation change; however, historically speaking query did return a PromiseArray. we may have broken something over time without realizing it. In today's world of async await and better promise knowledge, just working with the promise is preferred anyway.