fix permalink to respect baseURL

[ananay-22]

Noticed that the theme would break when I deployed to GH Pages because it ignores the baseURL (which is impossible to avoid with GH Pages specifically, and does require a nice bit of configuration if done after building with some nginx rule replacement etc).

This was being caused due to the fact that there was a use of 'RelPermaLink' instead of 'PermaLink' - adding in those changes in this PR

[panr]

Hey, two things:

• can you provide some kind of comparison/preview for this (what if someone has set baseURL, what if hasn't, what about multiple domains)? This is a breaking change so we must be sure that it won't break anything. I remember that we already did some fixes regarding nginx few years ago...
• are you sure that .PermaLink (camel case) is working? Because I think it should be .Permalink...