[dotnet] Add dotnet projects and examples

+ Sitemap generator I created while learning the dispose pattern
+ Testing project for learning general C#

dotnet/sitemap/ConsoleApp/Program.cs

@@ -0,0 +1,12 @@
+using SiteMapLibrary;
+
+// Create an XmlManager to use for generating our sitemap; Provide a file path (and optional Xml settings; See ctor)
+var mgr = new XmlManager("/home/kapper/Code/klips/dotnet/sitemap/ConsoleApp/TestFiles/sitemap.xml");
+// If we want to output the sitemap to the console, instead of saving to a file
+// var mgr = new XmlManager("Console.Out");
+
+// Provide a base URL to start crawling, an XmlManager, and a Regex pattern to use for matching URLs while crawling
+using SiteMap siteMap = new SiteMap("https://knoats.com", mgr,
+  new("(http?s://knoats.com(?!.*/dist/|.*/settings/|.*/register/|.*/login/|.*/uploads/|.*/export/|.*/search?).*?(?=\"))"));
+// Start crawling; When this returns, we have visited all found URLs and wrote them to our sitemap
+await siteMap.Crawl();