docs: add missing space (solana-foundation#3689)

Author: tobeycodes

docs/content/docs/tokens/extensions.mdx

@@ -10,7 +10,7 @@ description:
 
 The Token Extensions Program (Token 2022) provides additional features through
 additional instructions referred to as extensions. Extensions are optional
-functionality that can be added to a token mint or token account.You can find
+functionality that can be added to a token mint or token account. You can find
 the implementation of these extension instructions in the Token Extensions
 Program
 [source code](https://github.com/solana-program/token-2022/tree/main/program/src/extension).