fix(docs): buy button text colour in dark mode (#31985)

docs/tailwind.config.js

@@ -4,7 +4,7 @@ module.exports = {
   corePlugins: {
     preflight: false, // disable Tailwind's reset
   },
-  content: ['./src/**/*.{js,jsx,ts,tsx}', './{docs,blog}/**/*.{md,mdx}'], // my markdown stuff is in ../docs, not /src
+  content: ['./docusaurus.config.js', './src/**/*.{js,jsx,ts,tsx}', './{docs,blog}/**/*.{md,mdx}'], // my markdown stuff is in ../docs, not /src
   darkMode: ['class', '[data-theme="dark"]'], // hooks into docusaurus' dark mode settings
   theme: {
     extend: {