Suggest using streamreader instead of iterating over the stream

In the recommended section, you should suggest the use of StreamReader instead of manually iterating over the Stream :
using (var plainTextReader = new StreamReader(cryptoStream))
{
return plainTextReader.ReadToEnd();
}

reference : https://stackoverflow.com/questions/69911084/problem-updating-to-net-6-encrypting-string

Thanks !

---
#### Document Details

⚠ *Do not edit this section. It is required for learn.microsoft.com ➟ GitHub issue linking.*

* ID: 8ad66e79-695d-65b2-c85a-b857283e9aee
* Version Independent ID: febfa9c4-1fb2-0bc6-d23a-ed2e9425aeed
* Content: [Breaking change: Partial and zero-byte reads in DeflateStream, GZipStream, and CryptoStream - .NET](https://learn.microsoft.com/en-us/dotnet/core/compatibility/core-libraries/6.0/partial-byte-reads-in-streams)
* Content Source: [docs/core/compatibility/core-libraries/6.0/partial-byte-reads-in-streams.md](https://github.com/dotnet/docs/blob/main/docs/core/compatibility/core-libraries/6.0/partial-byte-reads-in-streams.md)
* Product: **dotnet-fundamentals**
* GitHub Login: @gewarren
* Microsoft Alias: **gewarren**