Change LOCAL_WORKDIR_PATH to `pwd` in the README + rewrite some sentences
Change LOCAL_WORKDIR_PATH to `pwd` in the README + rewrite some sentences

When I was running the Docker commands, it wasn't obvious to me that LOCAL_WORKDIR_PATH was supposed to be the directory where this repo was checked out. Using `pwd` is simple and should work for everyone on Linux or Mac.

SoftwareMansion/jsc-android-buildscripts,SoftwareMansion/jsc-android-buildscripts,SoftwareMansion/jsc-android-buildscripts