Restore & pimp docker docs in README, now that Docker build has been fixed by Jia (thanks Jia) (fix #848)

Dockerfile

@@ -1,19 +1,3 @@
-# This Dockerfile is designed to be used like the "normal" app.
-# By default, the command `nativefier --help` will be executed.
-# Before you can use the image, you have to build it:
-# 
-#     docker build -t local/nativefier .
-#  
-# After that, you can build your first nativefier app to the local `$TARGET-PATH`.
-# Ensure you have write access to the `$TARGET-PATH`:
-# 
-#     docker run -v $TARGET-PATH:/target local/nativefier https://my-web-app.com/ /target/
-# 
-# You can also pass nativefier flags, and mount additional volumes to provide
-# local files. For example, to use a icon:
-# 
-#     docker run -v $PATH_TO_ICON/:/src -v $TARGET-PATH:/target local/nativefier --icon /src/icon.png --name whatsApp -p linux -a x64 https://my-web-app.com/ /target/
-
 FROM node:12-stretch
 LABEL description="Debian image to build nativefier apps"
 

README.md

@@ -40,9 +40,7 @@ through the numerous open tabs when I was using [Facebook Messenger](https://mes
     - [Wine](https://www.winehq.org/) to package Windows apps under non-Windows platforms.
       Make sure `wine` is in your system `$PATH`.
 
-```bash
-npm install -g nativefier
-```
+Then, install Nativefier globally with  `npm install -g nativefier`
 
 ## Usage
 
@@ -59,6 +57,26 @@ to learn about other command-line flags usable to configure the packaged app.
 To have high-resolution icons used by default for an app/domain, please
 contribute to the [icon repository](https://github.com/jiahaog/nativefier-icons)!
 
+## Usage with Docker
+
+Nativefier is also usable from Docker.
+- Pull the latest stable image from Docker Hub: `docker pull jiahaog/nativefier`
+- ... or build the image yourself: `docker build -t local/nativefier .`
+  (in this case, replace `jiahaog/` in the below examples with `local/`)
+
+By default, the command `nativefier --help` will be executed.
+To build e.g. a Gmail nativefier app to a writable local `~/nativefier-apps`,
+
+```bash
+docker run -v ~/nativefier-apps:/target/ jiahaog/nativefier https://mail.google.com/ /target/
+```
+
+You can pass Nativefier flags, and mount volumes to provide local files. For example, to use an icon,
+
+```bash
+docker run -v ~/my-icons-folder/:/src -v $TARGET-PATH:/target jiahaog/nativefier --icon /src/icon.png --name whatsApp -p linux -a x64 https://web.whatsapp.com/ /target/
+```
+
 ## Development
 
 Help welcome on [bugs](https://github.com/jiahaog/nativefier/issues?q=is%3Aopen+is%3Aissue+label%3Abug) and