remove copy link URL functionality - see #34

as per the readme:

This plugin used to be called "Copy Image and URL context menu". It had link URL copying functionality (see 1.5.2 and prior), but that was removed when it was included in Obsidian 1.5.

Full Changelog: https://github.com/NomarCub/obsidian-copy-url-in-preview/compare/1.5.2…1.6.0