Fix typo in documentation

doc/creating-tasks.markdown

@@ -1,4 +1,4 @@
-Creating tasks
+Creating Tasks
 ==============
 
 From the board, click on the plus sign next to the column name:
@@ -13,14 +13,14 @@ The only mandatory field is the title.
 
 Field description:
 
-- **Title**: The title of your task, that will be displayed on the board.
+- **Title**: The title of your task, which will be displayed on the board.
 - **Description**: Allow you to add more information about the task, the content can be written in [Markdown](http://kanboard.net/documentation/syntax-guide).
-- **Create another task**: Check this box if you want to create a similar task (fields will be prefilled).
+- **Create another task**: Check this box if you want to create a similar task (some fields will be pre-filled).
 - **Assignee**: The person that will work on the task.
-- **Category**: Only one category can be assign to a task.
+- **Category**: Only one category can be assigned to a task.
 - **Column**: The column where the task will be created, your task will be positioned at the bottom.
 - **Color**: Choose the color of the card.
-- **Complexity**: Used in agile project management (Scrum), the complexity or story points is a number that tells the team how hard the story is. Often, people use the fibonacci series.
+- **Complexity**: Used in agile project management (Scrum), the complexity or story points is a number that tells the team how hard the story is. Often, people use the Fibonacci series.
 - **Original Estimate**: Estimation in hours to complete the tasks.
 - **Due Date**: Overdue tasks will have a red due date and upcoming due dates will be black on the board. Several date format are accepted in addition to the date picker.