document summary in the library is not correct

I don't know where to submit this comment. The document summary in the library dll is showing wired stuff as below, which should be fixed. Similar issue happend in FromException method.

```
// Summary:
// Creates a System.Threading.Tasks.Task`1 that's completed successfully with
// the specified result.
```

---
#### Document Details

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

* ID: 2404c89d-d864-dc42-bcfe-837ee5dcc706
* Version Independent ID: 6abd1553-8d5b-9049-98af-9c1a0272ebac
* Content: [Task.FromResult(TResult) Method (System.Threading.Tasks)](https://docs.microsoft.com/en-us/dotnet/api/system.threading.tasks.task.fromresult?view=netframework-4.7.2#feedback)
* Content Source: [xml/System.Threading.Tasks/Task.xml](https://github.com/dotnet/dotnet-api-docs/blob/master/xml/System.Threading.Tasks/Task.xml)
* Product: **dotnet-api**
* GitHub Login: @dotnet-bot
* Microsoft Alias: **dotnetcontent**