Issue-132: Add CONTRIBUTING.md and GitHub templates

.github/ISSUE_TEMPLATE.md

@@ -0,0 +1,11 @@
+| Q                      | A
+| ---------------------- | -----
+| Bug report?            | yes/no
+| Feature request?       | yes/no
+| BC Break report?       | yes/no
+| RFC?                   | yes/no
+| Affected image and tag | carcel/image:tag
+
+<!--
+- Please replace this comment by the description of your issue.
+-->

.github/PULL_REQUEST_TEMPLATE.md

@@ -0,0 +1,23 @@
+## Description
+
+<!--
+- Please fill in this template according to the PR you're about to submit.
+- Replace this comment by a description of what your PR is solving.
+- Bug fixes must be submitted against the lowest branch where they apply
+  (lowest branches are regularly merged to upper ones so they get the fixes too):
+  for example apply on `php-5.6` branch, it will then be merged in `php-7.0`, and so on up to `master`.
+- Documentation must be submitted against the master branch (it is not present in other branches to ease its maintenance).
+-->
+
+## Definition Of Done
+
+| Q                                 | A
+| --------------------------------- | ---
+| Added tests                       | Todo
+| Changelog updated                 | Todo
+| Documentation                     | -
+| Fixed tickets                     | #... <!-- #-prefixed issue number(s), if any -->
+
+`Todo`: Pending / Work in progress
+`OK`: Done / Validated
+`-`: Not needed

CONTRIBUTING.md

@@ -0,0 +1,10 @@
+# Contributing
+
+These Dockerfiles are not only made for my personal use, but for anybody who likes to develop on Akeneo or Symfony applications with Docker.
+
+I gladly accept any contributions: fixing typos, glitches, bugs, technical enhancements and new features.
+
+For technical enhancements and new features, please first have a look at [current issues](https://github.com/damien-carcel/Dockerfiles/issues).
+There may already be one, with details and ideas on how to implement it. You are welcome to pick it and propose a pull request if you'd like.
+
+If it does not already exist, please first open an issue to describe and discuss what you want to do, it will ease the merge of your pull request.

README.md

@@ -1,6 +1,6 @@
 # My Dockerfiles
 
-This repository contains my own docker images I use for Akeneo and other Symfony development. Feel free to use/adapt them if they fit your needs.
+This repository contains the Dockerfiles I use for Akeneo and other Symfony development. Feel free to use/adapt them if they fit your needs.
 
 | [Master][Master] | [php-7.1][php-7.1] | [php-7.0][php-7.0] | [php-5.6][php-5.6] |
 |:----------------:|:----------:|:----------:|:----------:|