Wrong link "Edit this page" when using Multisite

When we are using the [multisite setup](https://learn.getgrav.org/advanced/multisite-setup) of Grav, especially the one with subdirectories, the link to the Git resource for editing the page is wrong.

We expect to have:
`http://mygit/myproject/blob/master/pages/01.basic/01.sometopic//docs.md`
But we have instead:
`http://mygit/myproject/blob/master/sites/mysite/pages/01.basic/01.sometopic//docs.md`

Where `http://mygit/myproject/` is the root of the git project (on github, gitlab of any other system), the page is `/basic/sometopic` and the site in multisite setup is in the `mysite` directory. It means the doc is accessible via `http://mydoc/mysite/basic/sometopic`.

The `sites/mysite` is in the way. **Learn2** just imagine that the root folder of the doc is directly in `pages` folder when it is in `pages/sites/mysite`.