Fix and update Docker image

doc/build.md

@@ -94,13 +94,13 @@ grin client help
 ## Docker
 
 ```sh
-docker build -t grin .
+docker build -t grin -f etc/Dockerfile .
 ```
 
 You can bind-mount your grin cache to run inside the container.
 
 ```sh
-docker run -it -d -v $HOME/.grin:/root/.grin grin
+docker run -it -d -v $HOME/.grin:/root/.grin -f etc/Dockerfile grin
 ```
 
 ## Cross-platform builds

doc/build_ES.md

@@ -85,13 +85,13 @@ grin client help
 ## Docker
 
 ```sh
-docker build -t grin .
+docker build -t grin -f etc/Dockerfile .
 ```
 
 Puede ubicar la caché de Grin para que se ejecute dentro del contenedor
 
 ```sh
-docker run -it -d -v $HOME/.grin:/root/.grin grin
+docker run -it -d -v $HOME/.grin:/root/.grin -f etc/Dockerfile grin
 ```
 
 ## Compilación multiplataforma

etc/Dockerfile

@@ -1,18 +1,18 @@
 # Multistage docker build, requires docker 17.05
 
 # builder stage
-FROM rust:1.29.0 as builder
+FROM rust:1.30.1 as builder
 
 RUN set -ex && \
     apt-get update && \
     apt-get --no-install-recommends --yes install \
-        clang \
-        libclang-dev \
-        llvm-dev \
-        libncurses5 \
-        libncursesw5 \
-        cmake \
-        git
+    clang \
+    libclang-dev \
+    llvm-dev \
+    libncurses5 \
+    libncursesw5 \
+    cmake \
+    git
 
 WORKDIR /usr/src/grin