Improve documentation (#82)

* Propose new doc architecture

* Many improvements to documentation (styling, structure...)

* Remove modules added inadvertently + continue improving styling

* Swizzle navbar item to add support for custom icon

* Additional doc styling

* Setup docs for API and redirect homepage for docs

node_modules/.package-lock.json

@@ -0,0 +1,7 @@
+{
+  "name": "twenty",
+  "version": "1.0.0",
+  "lockfileVersion": 3,
+  "requires": true,
+  "packages": {}
+}