add docusaurus to social menu in footer (#4755)

docusaurus.config.js

@@ -841,6 +841,14 @@ const config = {
                   "./static/img/svgIcons/purple/dscvr.svg"
                 ),
               },
+              {
+                label: "Discord",
+                to: "https://discord.internetcomputer.org",
+                icon: "data:image/svg+xml,%3Csvg%20width%3D%2224%22%20height%3D%2224%22%20viewBox%3D%220%200%2024%2024%22%20fill%3D%22none%22%20xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F2000%2Fsvg%22%3E %3Cpath%20d%3D%22M19.3034%205.33716C17.9344%204.71103%2016.4805%204.2547%2014.9629%204C14.7719%204.32899%2014.5596%204.77471%2014.411%205.12492C12.7969%204.89144%2011.1944%204.89144%209.60255%205.12492C9.45397%204.77471%209.2311%204.32899%209.05068%204C7.52251%204.2547%206.06861%204.71103%204.70915%205.33716C1.96053%209.39111%201.21766%2013.3495%201.5891%2017.2549C3.41443%2018.5815%205.17612%2019.388%206.90701%2019.9187C7.33151%2019.3456%207.71356%2018.73%208.04255%2018.0827C7.41641%2017.8492%206.82211%2017.5627%206.24904%2017.2231C6.39762%2017.117%206.5462%2017.0003%206.68416%2016.8835C10.1438%2018.4648%2013.8911%2018.4648%2017.3082%2016.8835C17.4568%2017.0003%2017.5948%2017.117%2017.7434%2017.2231C17.1703%2017.5627%2016.576%2017.8492%2015.9499%2018.0827C16.2789%2018.73%2016.6609%2019.3456%2017.0854%2019.9187C18.8152%2019.388%2020.5875%2018.5815%2022.4033%2017.2549C22.8596%2012.7341%2021.6806%208.80747%2019.3034%205.33716ZM8.5201%2014.8459C7.48007%2014.8459%206.63107%2013.9014%206.63107%2012.7447C6.63107%2011.5879%207.45884%2010.6434%208.5201%2010.6434C9.57071%2010.6434%2010.4303%2011.5879%2010.4091%2012.7447C10.4091%2013.9014%209.57071%2014.8459%208.5201%2014.8459ZM15.4936%2014.8459C14.4535%2014.8459%2013.6034%2013.9014%2013.6034%2012.7447C13.6034%2011.5879%2014.4323%2010.6434%2015.4936%2010.6434C16.5442%2010.6434%2017.4038%2011.5879%2017.3825%2012.7447C17.3825%2013.9014%2016.5548%2014.8459%2015.4936%2014.8459Z%22%20fill%3D%22white%22%20%2F%3E %3C%2Fsvg%3E",
+                iconLight: getImageDataUrl(
+                  "./static/img/svgIcons/purple/discord.svg"
+                ),
+              },
             ],
           },
         ],