Allow for metadata population for each webpage

[brandenchan]

We now have descriptive tab titles (#280) but we don't yet have a means to populate a pages metadata. One method of implementing this was suggested in this comment. Such an implementation would be great.

We need also then to write metadata sections for each page.

[brandenchan]

@fstau , If we are also to implement this via headers in mdx, I am just wondering if the headers would be optional, or if we would have to create a header for every mdx page.

[fstau]

@brandenchan I can go ahead on the comment based solution. My proposal would be to use them if you provide them, - if not provided, we use the existing defaults?

[brandenchan]

Ok if it is possible to insert defaults in cases where the header hasn't been written yet, then we should go ahead with this.

[fstau]

@agnieszka-m would you like me to go ahead with this? If so, could you please tag it with should for a better overview over the SoW scope.

[agnieszka-m]

Yes, please go ahead.