fix: spelling mistake and grammar errors (#112)

docs/Overview.mdx

@@ -64,16 +64,16 @@ can be _read_, _write_, _delete_ or any other action as set by the developer.
 This is how Casbin is most widely used and its called the "standard"
 or classic `{ subject, object, action }` flow.
 
-Casbin is capable of handling many complex authorization senerios other than the standard flow.
+Casbin is capable of handling many complex authorization scenarios other than the standard flow.
 There can be addition of [roles (RBAC)](/docs/rbac), [attributes (ABAC)](/docs/abac) etc.
 
 ### What Casbin does:
 
 1. Enforce the policy in the classic ``{ subject, object, action }`` form 
-    or a customized form as you defined, both allow and deny authorizations are supported.
+    or a customized form as you defined. Both allow and deny authorizations are supported.
 2. Handle the storage of the access control model and its policy.
 3. Manage the role-user mappings and role-role mappings (aka role hierarchy in RBAC).
-4. Support built-in superuser like ``root`` or ``administrator``. A superuser can do anything without explicit permissions.
+4. Support built-in superusers like ``root`` or ``administrator``. A superuser can do anything without explicit permissions.
 5. Multiple built-in operators to support the rule matching. For example, ``keyMatch`` can map a 
     resource key ``/foo/bar`` to the pattern ``/foo*``.