docs(manage): update terraform provider (#8102)

# Which Problems Are Solved

Terraform provider docs without introcution and "here" links were hard
to search for.

# How the Problems Are Solved

Updated docs page

# Additional Changes

changed the slug for more clarity and added a redirect

docs/sidebars.js

@@ -154,11 +154,6 @@ module.exports = {
             "guides/manage/customize/restrictions",
           ],
         },
-        {
-          type: "category",
-          label: "Terraform",
-          items: ["guides/manage/terraform/basics"],
-        },
         {
           type: "category",
           label: "Users",
@@ -168,6 +163,7 @@ module.exports = {
             "guides/manage/customize/user-schema",
           ],
         },
+        "guides/manage/terraform-provider"
       ],
     },
     {