[Feature] Consider using GH token during linkcheck to avoid throttling by GH actions

[alessandrofelder]

Based on discussions at the group meeting today, it might be useful to implement the analogous PR to neuroinformatics-unit/neuroinformatics-unit.github.io#242 for BrainGlobe.

This issue will be addressed when

• we have confirmed this is useful
• we have implemented it

[IgorTatarnikov]

There are quite a few links that seem to be down/failing see here.