markdown.lang: link highlighting false positive due to greediness
In this sample:
This is a [reference link] followed by an [inline link](example.com).
[reference link]: example.com
GtkSourceView highlights the whole reference link] followed by an [inline link
as the link text:
(actually, this breaks GitLab's highlighting too, heh)
fccee8c5 built using the Flatpak manifest with Builder