Move the typography plugin config into extend

https://tailwindcss.com/docs/upgrading-to-v2#update-typography-and-forms-plugins
https://github.com/tailwindlabs/tailwindcss-typography/releases/tag/v0.3.0

web/themes/custom/opdavies/tailwind.config.js

@@ -21,8 +21,9 @@ module.exports = {
     whitelist: ['bg-gray-200']
   },
   theme: {
+    extend: {
       typography: (theme) => ({
-      default: {
+        DEFAULT: {
           css: {
             a: {
               color: theme('colors.blue.500')
@@ -52,7 +53,6 @@ module.exports = {
           }
         }
       }),
-    extend: {
       colors: {
         inherit: 'inherit',