Canvas provides a great feature to create a syllabus in a course. We generally encourage our instructors to create their content in the RCE (HTML) so that it is more accessible and usable than a PDF file or other document that have historically been used.
Today I helped an instructor make that conversion. He had previously add a link to his syllabus PDF file from the modules and I was surprised that I was unable to add a direct link to the Syllabus page.
A couple of posts from the community where others have inquired about the same thing:
Going from the insightful comment from James that the current behavior is because the syllabus is in the same category of course navigation items (links to list of assignments, list of quizzes, list of files, list of pages, or list of discussions). It makes sense to me that the those menu items that link to lists of content cannot be added, but I would argue that the Syllabus page is a different type of content more similar to an individual page or assignment that can be added to modules.
Although the Syllabus can be added to a prominent location in the course navigation (which is great), it would be fantastic if it could also be added as a module item directly to help instructors get that essential content in front of students.