Add global Gantt chart for all projects

docs/gantt-chart-projects.markdown

@@ -0,0 +1,16 @@
+Gantt chart for all projects
+============================
+
+The goal of this Gantt chart is to display an overview of all projects based on the start and end dates.
+
+- This Gantt chart is available in the project management section
+- Only project administrators and administrators can access to this section
+- Project administrators will see only projects where they are members
+
+![Gantt Chart for all projects](http://kanboard.net/screenshots/documentation/gantt-chart-all-projects.png)
+
+- The **start date** and the **end date** of projects are used to draw the chart
+- Horizontal bars can be resized and moved horizontally with your mouse
+- There is no vertical drag and drop
+- Project bars are displayed in black when there is no start or end date defined
+- The information tooltip show the list of project managers and standard members

docs/gantt-chart-tasks.markdown

@@ -1,7 +1,10 @@
-Gantt chart for projects
-========================
+Gantt chart for tasks
+======================
 
-The Gantt chart is available from the the action menu by project managers.
+The goal of this Gantt chart is to display a time based overview of the tasks for a given project.
+
+- The Gantt chart is available from the the action menu
+- Only project managers can access to this section
 
 ![Gantt Chart](http://kanboard.net/screenshots/documentation/gantt-chart-project.png)
 

docs/index.markdown

@@ -28,7 +28,8 @@ Using Kanboard
 - [Calendar](calendar.markdown)
 - [Budget](budget.markdown)
 - [Analytics](analytics.markdown)
-- [Gantt chart](gantt-chart.markdown)
+- [Gantt chart for tasks](gantt-chart-tasks.markdown)
+- [Gantt chart for projects](gantt-chart-projects.markdown)
 
 ### Working with tasks