Merge pull request #187 from 4jcraft/rm-rf-readme-update

removed rm -rf to -r, closes issue #185

README.md

@@ -122,7 +122,7 @@ meson setup build --reconfigure
 ...or to hard reset the build directory:
 
 ```bash
-rm -rf ./build
+rm -r ./build
 meson setup build
 ```