[documentation] improving formatting

Author: zombieFox

README.md

@@ -7,6 +7,8 @@ A neutral new tab page accented with a chosen colour. Customise the layout, styl
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 |[![nightTab](./src/icons/icon-48.png)](https://zombiefox.github.io/nightTab/)|[![Chrome](assets/browser-logos/chrome-48x48.png)](https://chrome.google.com/webstore/detail/nighttab/hdpcadigjkbcpnlcpbcohpafiaefanki)|[![Firefox](assets/browser-logos/firefox-48x48.png)](https://addons.mozilla.org/en-GB/firefox/addon/nighttab/)|[![coffee](https://cdn.buymeacoffee.com/buttons/bmc-new-btn-logo.svg)](https://www.buymeacoffee.com/zombieFox/)|
 
+---
+
 ### Features
 - Header
 - Greeting