Adding wiki data file to data formats doc

Adding wiki data file to data formats doc
editing wiki data

removed boilerplace from beginning of file
Added user_id_map

Added user_id_map
New Accessibility Chapter

Adding changes for accessibility
Accessibilty updates

Accessibilty updates
Accessibility edits

Accessibility edits
Merge pull request #1920 from edx/markhoeber/documentation/stud-1007

Adding accessibility guidelines to "Building a Course with edX Studio" documentation