Add usage information to the readme. (#3)

README.md

@@ -9,3 +9,27 @@
 [![Security Rating](https://sonarcloud.io/api/project_badges/measure?project=demaconsulting_TestResults&metric=security_rating)](https://sonarcloud.io/summary/new_code?id=demaconsulting_TestResults)
 
 The TestResults library supports saving test results to TRX files.
+
+
+## Usage
+
+The following code-snippet shows how to create a TRX test-results file.
+
+```csharp
+// Create a TestResults instance
+var results = new TestResults{Name = "SomeTests"};
+
+// Add some results
+results.Results.Add(
+    new TestResult{
+        Name = "Test1",
+        ClassName = "SomeTestClass",
+        CodeBase = "MyTestAssembly",
+        Outcome = TestOutcome.Passed
+    });
+
+// Save the results to file
+File.WriteAllText(
+    "results.trx",
+    TrxSerializer.Serialize(results));
+```