add creating new release guide

doc/make_release.md

+# Things to do when creating new release
+NOTE: This is a developer guide. If you are trying to install GitLab see the latest stable [installation guide](install/installation.md) and if you are trying to upgrade, see the [upgrade guides](update). 
+## Install guide up to date?
+
+* References correct GitLab branch `x-x-stable` and correct GitLab shell tag?
+
+## Make upgrade guide
+
+### From x.x to x.x
+
+#### 0. Any major changes? Database updates? Web server change? File strucuture changes?
+
+#### 1. Make backup
+
+#### 2. Stop server
+
+#### 3. Do users need to update dependencies like `git`?
+
+#### 4. Get latest code
+
+#### 5. Does GitLab shell need to be updated?
+
+#### 6. Install libs, migrations, etc.
+
+#### 7. Any config files updated since last release?
+
+Check if any of these changed since last release (~22nd of last month depending on when last release branch was created):
+
+* https://github.com/gitlabhq/gitlabhq/commits/master/lib/support/nginx/gitlab
+* https://github.com/gitlabhq/gitlab-shell/commits/master/config.yml.example
+* https://github.com/gitlabhq/gitlabhq/commits/master/config/gitlab.yml.example
+* https://github.com/gitlabhq/gitlabhq/commits/master/config/puma.rb.example
+* https://github.com/gitlabhq/gitlabhq/commits/master/config/database.yml.mysql
+* https://github.com/gitlabhq/gitlabhq/commits/master/config/database.yml.postgresql
+
+#### 8. Need to update init script?
+
+Check if changed since last release (~22nd of last month depending on when last release branch was created): https://github.com/gitlabhq/gitlabhq/commits/master/lib/support/init.d/gitlab
+
+#### 9. Start application
+
+#### 10. Check application status
+
+## Make sure code status is good
+
+* [![build status](http://ci.gitlab.org/projects/1/status.png?ref=master)](http://ci.gitlab.org/projects/1?ref=master) on ci.gitlab.org (master branch)
+
+* [![build status](https://secure.travis-ci.org/gitlabhq/gitlabhq.png)](https://travis-ci.org/gitlabhq/gitlabhq) on travis-ci.org (master branch)
+
+* [![Code Climate](https://codeclimate.com/github/gitlabhq/gitlabhq.png)](https://codeclimate.com/github/gitlabhq/gitlabhq)
+
+* [![Dependency Status](https://gemnasium.com/gitlabhq/gitlabhq.png)](https://gemnasium.com/gitlabhq/gitlabhq) this button can be yellow (small updates are available) but must not be red (a security fix or an important update is available)
+
+* [![Coverage Status](https://coveralls.io/repos/gitlabhq/gitlabhq/badge.png?branch=master)](https://coveralls.io/r/gitlabhq/gitlabhq)
+
+## Make release branch