updated readme

README.md

@@ -14,7 +14,13 @@ Yaco can be built out of source using the scripts provided under ${YACO_ROOT}/sc
 In order to build yaco along with all its dependencies on levante for eg., one should do the following (preferably on an interactive node): 
 ```
 mkdir build && cd build 
-../scripts/setup/levante.intel-ompi412.sh --yaco-root ..
+../scripts/setup/levante.intel-ompi412.sh --yaco-root .. 
+# this would build with following folder-structure (any arbitrary build folder can be used): 
+# ${yaco-commit-hash}-{compiler} would be the folder created into it and everything will be built there
+# build-folder: $(pwd)/build/${yaco-commit-hash}-{compiler}
+# externals : $build-folder/externals/
+# install-externals : $build-folder/install/
+# yaco : $build-folder/
 
 # building only one particular dependency (healpix as an example)
 # for further examples: look into scripts/setup/build_dependencies