Include documentation in the application

doc/installation.markdown

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+Installation
+============
+
+Requirements
+------------
+
+- Apache or Nginx
+- PHP >= 5.3.3 (Kanboard is compatible with PHP 5.3, 5.4, 5.5, 5.6 and 7.0)
+- PHP extensions required: mbstring, gd and pdo_sqlite
+- A modern web browser
+
+From the archive (stable version)
+---------------------------------
+
+1. You must have a web server with PHP installed
+2. Download the source code and copy the directory `kanboard` where you want
+3. Check if the directory `data` is writeable
+4. With your browser go to <http://yourpersonalserver/kanboard>
+5. The default login and password is **admin/admin**
+6. Start to use the software
+7. Don't forget to change your password!
+
+Note: The folder data is the location where Kanboard stores uploaded files as well as the Sqlite database.
+
+From the repository (development version)
+-----------------------------------------
+
+You must install [composer](https://getcomposer.org/) to use this method.
+
+1. `git clone https://github.com/fguillot/kanboard.git`
+2. `composer install`
+3. Go to the third step just above
+
+Note: This method will install the **current development version**, use at your own risk.
+
+Security
+--------
+
+- Don't forget to change the default user/password
+- Don't allow everybody to access to the directory `data` from the URL. There is already a `.htaccess` for Apache but nothing for Nginx.