Add precision about cmake cache
diff --git a/configs/README.txt b/configs/README.txt
index bab500d..f543002 100644
--- a/configs/README.txt
+++ b/configs/README.txt
@@ -18,7 +18,7 @@
 
    Or, using cmake:
 
-    rm CMakeCache.txt
+    find . -iname '*cmake*' -not -name CMakeLists.txt -exec rm -rf {} +
     CFLAGS="-I$PWD/configs -DPOLARSSL_CONFIG_FILE='<foo.h>'" cmake .
     make