A syllabus statement, addressing students with disabilities, will let them know that while you are approachable and willing to work with them. It is the student's responsibility to communicate their needs to you in advance. The syllabus statement might read:
"Brown University is committed to full inclusion of all students. Students who, by nature of a documented disability, require academic accommodations should contact the professor during office hours. Students may also speak with Student and Employee Accessibility Services at 401-863-9588 to discuss the process for requesting accommodations."
An alternative wording:
"ACCOMMODATIONS FOR STUDENTS WITH DISABILITIES: Any student with a documented disability is welcome to contact me as early in the semester as possible so that we may arrange reasonable accommodations. As part of this process, please be in touch with Student and Employee Accessibility Services by calling 401-863-9588 or online at http://brown.edu/Student_Services/Office_of_Student_Life/seas/index.html
Faculty may consult with SEAS at any time regarding syllabus statements or any other disability-related matter.