Dockerfile: - Use the most recent stable debian (buster) instead of the previous one - Build version 1.39.11 by default instead of 1.38.43 - Fix small typo in the comments Makefile and README.MD: Fix incorrect name of image on dockerhub.
As a continuation from: https://github.com/emscripten-core/emscripten/issues/8742 This PR provides adopted Dockerfile from https://github.com/trzecieu/emscripten-docker/blob/master/docker/trzeci/emscripten-fastcomp/Dockerfile which supports builds: * fastcomp * upstream Features: * An image can be build with fastcomp and upstream version of Emscripten SDK * It applies some extra size optimizations (that might be removed in sake of clarity / stability) * It creates conventional `1000:1000` user `emscripten` * It creates extra entrypoint that mitigates running as non-root user (Some context: https://trzeci.eu/fixing-permission-of-files-created-from-docker/) * It has simple-stupid tests performed during building