Revert docs update

docs/.vuepress/theme/components/Navbar.vue

@@ -20,18 +20,6 @@
       >{{ $siteTitle }}</span>
     </router-link>
 
-    <span
-      class="deprecated"
-      v-if="isAlpha">
-      Deprecated docs -
-      <router-link
-        :to="$localePath"
-        class="home-link"
-      >
-        current version
-      </router-link>
-    </span>
-
     <div
       class="links"
       :style="linksWrapMaxWidth ? {
@@ -55,8 +43,7 @@ export default {
   components: { SidebarButton, NavLinks, AlgoliaSearchBox, SearchBox},
   data () {
     return {
-      linksWrapMaxWidth: null,
-      isAlpha: false
+      linksWrapMaxWidth: null
     }
   },
   mounted () {
@@ -72,7 +59,6 @@ export default {
     }
     handleLinksWrapWidth()
     window.addEventListener('resize', handleLinksWrapWidth, false)
-    this.isAlpha = /documentation\/3.0.0-alpha.x/.test(window.location.href)
   },
   computed: {
     algolia () {