chore: update vuepress config to reflect new default branch naming (#11769)

docs/.vuepress/config.js

@@ -47,8 +47,8 @@ module.exports = {
         "key": "v0.45"
       },
       {
-        "label": "master",
-        "key": "master"
+        "label": "main",
+        "key": "main"
       }
     ],
     topbar: {
@@ -185,7 +185,7 @@ module.exports = {
             {
               title: "Contributing to the docs",
               url:
-                "https://github.com/cosmos/cosmos-sdk/blob/master/docs/DOCS_README.md"
+                "https://github.com/cosmos/cosmos-sdk/blob/main/docs/DOCS_README.md"
             },
             {
               title: "Source code on GitHub",

docs/.vuepress/enhanceApp.js

@@ -1,7 +1,7 @@
 export default ({ router }) => {
   router.addRoutes([
-    { path: '/master/spec/*', redirect: '/master/modules/' },
-    { path: '/master/spec/governance/', redirect: '/master/modules/gov/' },
+    { path: '/main/spec/*', redirect: '/main/modules/' },
+    { path: '/main/spec/governance/', redirect: '/main/modules/gov/' },
     { path: '/v0.41/', redirect: '/v0.42/' },
     { path: '/v0.43/', redirect: '/v0.44/' },
   ])