Update h4 styles

[davepagurek]

Before	After

Other spots that used h4 have been updated to look the same as before (and it seems to be just these two cases according to this search https://github.com/search?q=repo%3Aprocessing%2Fp5.js-website%20h4&type=code):

• The param name in the list of parameters in a reference page:

  
• The author on education resources entries:

[Qianqianye]

Thanks @davepagurek!