missing alt attribute in api documentation
Description
The placeholder/sample code for Staff Images does not include an alt attribute in this file: docs/en_us/platform_api/source/course_info.rst
It does in the following:
common/lib/xmodule/xmodule/templates/about/overview.yaml
common/test/data/2014/about/overview.html
common/test/data/course_info_updates/about/overview.html
common/test/data/manual-testing-complete/about/overview.html
For consistency, alt="Course Staff Image ##" should be added for both images.
