Improve installation instructions

Dockerfile

@@ -1,14 +1,6 @@
 FROM node:7.4-wheezy
 
-# Global install yarn package manager
-RUN apt-get update && apt-get install -y curl apt-transport-https && \
-    curl -sS https://dl.yarnpkg.com/debian/pubkey.gpg | apt-key add - && \
-    echo "deb https://dl.yarnpkg.com/debian/ stable main" | tee /etc/apt/sources.list.d/yarn.list && \
-    apt-get update && apt-get install -y yarn
-
 WORKDIR /app
 
 # Do our application specific stuff
 COPY . /app/
-
-RUN yarn

README.md

@@ -2,26 +2,21 @@
 
 ## Install
 
-Make sure you have Docker up and running.
+Build your Docker container.
 
-```
-# Make sure docker-machine is up
-docker-machine start <name of your machine>
-eval $(docker-machine env <name of your machine>)
-
-# Before running, build your docker container
+```sh
 docker build . -t serverless:reasonml
 ```
 
-Run the following script to install the build environment inside docker:
+Run the following script to install the build environment inside Docker: 
 
-```
-./install
+```sh
+./install.sh
 ```
 
 Build the container manually:
 
-```
+```sh
 # Use this script to automatically run the built container
 ./run.sh
 ```
@@ -31,7 +26,7 @@ Build the container manually:
 1. Create a ReasonML file with a name of your choice e.g. myCustomFunction.re
 2. Add your function to `serverless.yml` e.g.
 
-```
+```yml
 functions:
   myFunction:
     handler: myCustomFunction