README.md: notice on autotools and Makefile

not much tested anymore

Author: MartinPulec

README.md

@@ -195,8 +195,8 @@ In Linux, you may also consider `-DUSE_NATIVE_CPU_ARCH=ON` for optimized
 CPU code build (`-march=native` added to compiler flags).
 
 In Linux, you can also use **autotools** to create a build recipe for
-the library and the application or a plain old _Makefile.bkp_. However,
-_cmake_ is recommended.
+the library and the application or a plain old _Makefile.bkp_. Those ways
+are maintained just a little so please let us know in case of problems.
 
 Usage
 -----