Update README.md

README.md

@@ -82,7 +82,7 @@ conan remote add conan-transit https://api.bintray.com/conan/conan/conan-transit
 - [protocol buffers v3.5.1](https://github.com/protocolbuffers/protobuf/releases/tag/v3.5.1).
 Build using the -fPIC option and install:
 ```bash
-./configure CXXFLAGS=-fPIC
+./configure CXXFLAGS=-fPIC --prefix=/usr
 make 
 sudo checkinstall
 ```