Updated build instructions

README.md

@@ -13,9 +13,9 @@ The repo uses CMake for building the extension. To build, first create a `build`
 % cd build
 % cmake ..
 ```
-Then you build the source with 
+Then you build the source with the default build tool (`make`, `ninja`, ...) or let CMake figure it out
 ```
-% make
+% cmake --build .
 ```
 and you should have your extension module built and ready for use. The resulting module is automatically copied to the src directory.