Add project description field.

Description is shown in a popup when hovering the 'information' icon, like column description,
which is shown in project list on dashboard and in board's title.

This is useful to document the categories and colors used in the project.

app/Controller/Board.php

@@ -127,6 +127,7 @@ class Board extends Base
             'swimlanes' => $this->board->getBoard($project['id']),
             'categories' => $this->category->getList($project['id'], false),
             'title' => $project['name'],
+            'description' => $project['description'],
             'no_layout' => true,
             'not_editable' => true,
             'board_public_refresh_interval' => $this->config->get('board_public_refresh_interval'),
@@ -187,6 +188,7 @@ class Board extends Base
             'swimlanes' => $this->board->getBoard($project['id']),
             'categories' => $this->category->getList($project['id'], true, true),
             'title' => $project['name'],
+            'description' => $project['description'],
             'board_selector' => $board_selector,
             'board_private_refresh_interval' => $this->config->get('board_private_refresh_interval'),
             'board_highlight_period' => $this->config->get('board_highlight_period'),