add intro message to readme

hacksdump · hacksdump · commit f55daf43a580 · 2020-07-31T22:52:21.000+05:30
diff --git a/README.md b/README.md
@@ -1,5 +1,9 @@
 # C++ | Google Test | Gcov | Lcov
 
+This repository demonstrates how to get coverage results with Google Test.
+
+The CMake flag `set(CMAKE_CXX_FLAGS --coverage)` does the main job.
+
 ## Build instructions
 
 ```shell script
