This commit moves the Features page from the section for developers
to the top level in the page tree. This involves:
- Moving the source files to the *features* folder from the *using-scylla* folder.
- Moving images into *features/images* folder.
- Updating references to the moved resources.
- Adding redirections to the moved pages.
Closesscylladb/scylladb#20401
360f7b3d33