DOCSP-18828 rust order (#765)

* DOCSP-18828: update driver order for Rust

Author: Chris Cho

source/index.txt

@@ -23,8 +23,8 @@ MongoDB Drivers
    Python Drivers </python>
    Ruby Driver  <https://docs.mongodb.com/ruby-driver/current/>
    Ruby Mongoid ODM  <https://docs.mongodb.com/mongoid/current/>
+   Rust Driver </rust>
    Scala Driver </scala>
    Swift Driver </swift>
-   Rust Driver </rust>
    About Compatibility Tables <about-compatibility>
    Security </security>