`ArrayList` incorrect remarks

### Type of issue

Other (describe below)

### Description

It says:

> Using multidimensional arrays as elements in an ArrayList collection is not supported.

This is factually false. Consider

```powershell
$al = [System.Collections.ArrayList]::new();
$al.Add([int[,]]::new(2, 2)) | Out-Null;
$al.GetType(); # ArrayList
$al[0].GetType(); # int[,]
$al; # four 0's
```

Did the author intend to mean

> If you add an array as an element to an ArrayList `al`, you cannot access the indexer of that array without casting, so `al[0][0]` doesn't work. You need to write `((int[,])al[0])[0, 0]` if `al[0]` is `int[,]`.

### Page URL

https://learn.microsoft.com/en-us/dotnet/api/system.collections.arraylist?view=net-10.0#remarks

### Content source URL

https://github.com/dotnet/dotnet-api-docs-temp/blob/live/xml/System.Collections/ArrayList.xml

### Document Version Independent Id

6a622c60-e7f9-3105-0b79-96b74ed08569

### Platform Id

8cf9e552-6fbf-c688-1a3c-ecf392888b8a

### Article author

@dotnet-bot

Open xml/System/ArrayList.xml from the content source URL and locate the ArrayList remarks containing the claim about multidimensional arrays. Compare that wording with the PowerShell example and the proposed clarification in the issue. Done means the inaccurate statement is corrected in the ArrayList remarks and the page accurately describes the indexing behavior.

Written by the indexing model from the issue text.