HG-193: Add link to the User login page

Add link to the User login page. 

The link has `./` in front of it because the browser treats `Special:UserLoigin` as `UserLogin` page over the `Special` protocol.
Can you clean up this SVG to shrink the file size? Remove the unnecessary comments, unneeded id attributes, and other stuff that Illustrator adds, which aren't actually needed for the icon.