Fix README formatting

Author: govert

RtdArrayTest/README.md

@@ -3,14 +3,14 @@
 This sample was created to provide a simple RTD server to check the behaviour of RTD functions when called from array formulas.
 
 The wrapper function has signature
-    ```c#
+   ```cs
 	public static object RtdArrayTest(string prefix)
-	```
+   ```
 and returns a 2x1 array.
 
-The function can be called from Excel as an array formula (with Ctrl+Shift+Enter) using another reference as the "prefix".
-	```
-	{=RtdArrayTest(A1)}
-	```
+The function can be called from Excel as an array formula (with Ctrl+Shift+Enter) using another cell as the "prefix":
+   ```
+    {=RtdArrayTest(D1)}
+   ```
 
-The implementation of the RTD server is based on the Excel-DNA base class `ExcelRtdServer`, and just uses a Timer to update the topics.
+The implementation of the RTD server is based on the Excel-DNA base class `ExcelRtdServer`, and just uses a Timer to update the topics.