Support <inheritdoc/> when generating documentation

[jmasek]

Product and Version Used:
Roslynator Command Line Tool version 0.3.3.0 (Roslyn version 4.2.0.0)

Steps to Reproduce:

• Create an interface and document its methods.
• Create a class that implements the interface and use /// <inheritdoc/> directive to use the documentation from interface.

Actual Behavior:

public interface IClient
{
    /// <summary>
    /// Sends the message to the stream
    /// </summary>
   public Task SendMessageAsync();
}

public sealed class Client: IClient
{
    /// <inheritdoc/>
    public async Task SendMessageAsync(){...}
}

No description is shown in documentation for Client:SendMessageAsync()

Expected Behavior:
https://docs.microsoft.com/en-us/dotnet/csharp/language-reference/xmldoc/recommended-tags#inheritdoc

Description is shown in documentation for Client:SendMessageAsync()

[josefpihrt]

https://tunnelvisionlabs.github.io/SHFB/docs-master/SandcastleBuilder/html/79897974-ffc9-4b84-91a5-e50c66a0221d.htm