Tolerate errors, remove `set -e`

When calling `khronos-mirror-docs opengl`, the call to wget that
downloaded all the registry files was exiting with an error code despite
downloading everything it needed to. Because of `set -e`, the script
exited early, preventing the quick reference cards from downloading.
Fix OpenGL 3.2 quick reference card

- Symlink rather than move so that wget won't redownload the file.
- Fix name from "opengl33" to "opengl32".