Prose conversion

[Hackin7]

For now I edited the error.hbs to use the prose class. I have also updated tailwind.config.js so that the prose class doesn't overwrite the inner classes as much

[wei2912]

One current issue with the use of the prose class is that the font family of the headings are different (see the below two images for comparison):

(with prose)

(without prose)

Before this PR can be merged, the font families and sizes will need to be standardised.

[wei2912]

Practically all pages, other than home.hbs and page-stories.hbs, are already using the prose class for all typography. Moving forward, I think we can continue to adopt the use of prose for multiple paragraphs of text while avoiding its use for more complex components, e.g. article display.

[wei2912]

Please see the above comments, thanks! Let me know if you have any queries on what to change.

[Hackin7]

For now I'm still not too sure of the best way to do it, but in home.hbs and page-stories.hbs, I made the headings use the prose class (by wrapping the heading around a span element with the prose class)
This way, the overall style can be customised by modifying the prose class in tailwind.config.js