docker-compose fixes

- Swapped package `libpng12-dev` with `libpng-dev` in PHP Dockerfile
- Fixed path of `sprinkles.example.json` and `sprinkles.json` in README.md

Author: Silic0nS0ldier

CHANGELOG.md

@@ -5,6 +5,11 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/)
 and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.html).
 
+## [Unreleased]
+### Fixed
+- Corrected Docker `README.md` to refer to updated `sprinkles.json` and `sprinkles.example.json` locations.
+- Replaced `libpng12-dev` which has been dropped since Ubuntu 16.04 with `libpng-dev` in PHP `Dockerfile`.
+
 ## v4.1.21
 - Locked Whoops to version 2.2.1 until they fix that [`[internal]` issue](https://github.com/filp/whoops/issues/598).
 

docker/README.md

@@ -4,7 +4,7 @@ First, install [Docker Compose](https://docs.docker.com/compose/install/).
 
 Second, initialize a new UserFrosting project:
 
-1. Copy `app/sprinkles/sprinkles.example.json` to `app/sprinkles/sprinkles.json`
+1. Copy `app/sprinkles.example.json` to `app/sprinkles.json`
 2. Run `chmod 777 app/{logs,cache,sessions}` to fix file permissions for web server. (NOTE: File
    permissions should be properly secured in a production environment!)
 2. Run `docker-compose run composer install` to install all composer modules.

docker/php/Dockerfile

@@ -2,7 +2,7 @@ FROM php:7.0-fpm
 RUN apt-get update && apt-get install -y \
         libfreetype6-dev \
         libjpeg62-turbo-dev \
-        libpng12-dev \
+        libpng-dev \
     && docker-php-ext-configure gd --with-freetype-dir=/usr/include/ --with-jpeg-dir=/usr/include/ \
     && docker-php-ext-install -j$(nproc) gd \
     && docker-php-ext-install -j$(nproc) pdo pdo_mysql