docs: Add "Token Extensions" in the top-level doc (#6183)

* docs: Add "Token Extensions" in the top-level doc

* Update docs/src/token-2022.md

Co-authored-by: jon wong <[email protected]>

---------

Co-authored-by: jon wong <[email protected]>

Author: joncinque

docs/src/token-2022.md

@@ -5,8 +5,8 @@ title: Token-2022 Program
 A token program on the Solana blockchain, defining a common implementation for
 fungible and non-fungible tokens.
 
-The Token-2022 Program is a superset of the functionality provided by the
-[Token Program](token.mdx).
+The Token-2022 Program, also known as Token Extensions, is a superset of the
+functionality provided by the [Token Program](token.mdx).
 
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