POST `/api/v0/main-frontend/courses/:course_id/upload` - Uploads a media (image, audio, file) for the course from Gutenberg page edit. Put the the contents of the media in a form and add a content type header multipart/form-data. # Example Request: ```http POST /api/v0/main-frontend/pages/d86cf910-4d26-40e9-8c9c-1cc35294fdbb/upload HTTP/1.1 Content-Type: multipart/form-data BINARY_DATA ```