Expose documentation how to make VLC portable

As explained in the forums, VLC can be made portable by simply adding a "portable" sub folder.

Since the wiki seems to be closed for public editing, can you add this info to https://wiki.videolan.org/Windows/#Portable_VLC (regardless of the PortableApps version)?

To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information