Update docs website (#4564)

* update theme

* Update version

* Updated Questions section in the footer

* Remove links to Riot chat

* Typo

* Add Discord link

* Update docs theme to the latest version

* Use docs-staging branch for staging website

* Resolve merge conflicts

* Update version

* Add google analytics

Co-authored-by: Marko <marbar3778@yahoo.com>

docs/.vuepress/styles/index.styl

@@ -1,3 +1,3 @@
 :root
-  --accent-color #00BB00
+  --accent-color #018A01
   --background #222222

docs/package.json

@@ -4,7 +4,8 @@
   "description": "Welcome to the Tendermint Core documentation!",
   "main": "index.js",
   "dependencies": {
-    "vuepress-theme-cosmos": "^1.0.150"
+    "@vuepress/plugin-google-analytics": "^1.3.1",
+    "vuepress-theme-cosmos": "^1.0.156"
   },
   "scripts": {
     "preserve": "./pre.sh",
@@ -16,4 +17,4 @@
   },
   "author": "",
   "license": "ISC"
-}
+}