Merge pull request #1225 from google/nmakedoc

Clarified that 'nmake' must be run before 'nmake check'.

cmake/README.md

diff --git a/cmake/README.md b/cmake/README.md
index 58aae8e..1e7410d 100644
--- a/cmake/README.md
+++ b/cmake/README.md
@@ -157,7 +157,8 @@
 Testing
 =======
 
-To run unit-tests:
+To run unit-tests, first you must compile protobuf as described above.
+Then run:
 
      C:\Path\to\protobuf\cmake\build\release>nmake check