updating Hashset`1.xml for Try .NET

[WilliamAntonRohm]

samples PR is dotnet/samples#1533

[WilliamAntonRohm]

@mairaw, @BillWagner -- please review these updates at your convenience.

[Thraka]

Just FYI I tried the first snippet on the hashset article and it wouldn't compile and run in the try browser

[WilliamAntonRohm]

@Thraka -- Andy, that is strange. The updated sample files have been merged, so this snippet should be working.

@mairaw, @BillWagner -- in that generated article's HTML page source, I see my own fork referenced (?!) for the data-src -- how can I fix that?

<pre><code class="lang-csharp" data-interactive="csharp" data-src="https://github.com/WilliamAntonRohm/dotnet-api-docs/blob/hashset/snippets/csharp/VS_Snippets_CLR_System/system.Collections.Generic.HashSet_UnionWith/cs/Program.cs" name="System.Collections.Generic.HashSet_UnionWith#01">using System;

[mairaw]

After the samples are merged, two things need to happen:

• An internal build of the target branch needs to be done (but since it has been so long the master branch has been built many times)
• This PR needs to be rebuilt

[WilliamAntonRohm]

Replaced by new PR #3430.