Add a more portable version of build/install doc in README.

Author: viferga

README.md

@@ -515,12 +515,10 @@ Usually the developer is the same who does the fork, but it may be possible that
 Follow these steps to build and install **METACALL** manually.
 
 ``` sh
-git clone --recursive https://github.com/metacall/core.git
+git clone https://github.com/metacall/core.git
 mkdir core/build && cd core/build
 cmake ..
-make
-make test
-sudo make install
+cmake --build . --target install
 ```
 
 ### 6.1 Build Options