Update test-markdown-basics.md

Add carriage return tests

doc/developer/tests/test-markdown-basics.md

@@ -18,6 +18,18 @@ Normal Text_
 _Normal Text  
 _Normal Text*
 
+### Carriage Return  
+
+**The following text should render as:**  
+Line #1 followed by Line #2  
+Line #2 followed by one blank line
+
+Line #3 followed by one blank line
+
+
+Line #4 following one blank line  
+
+
 ### Code Blocks
 
 ```