Correct findAssociatedTokenAddress JS sample

Fixes #869

Author: mvines

docs/src/associated-token-account.md

@@ -53,14 +53,14 @@ async function findAssociatedTokenAddress(
     walletAddress: Pubkey,
     tokenMintAddress: Pubkey
 ): Promise<PublicKey> {
-    return PublicKey.findProgramAddress(
+    return (await PublicKey.findProgramAddress(
         [
             walletAddress.toBuffer(),
             SPL_TOKEN_PROGRAM_ID.toBuffer(),
             tokenMintAddress.toBuffer(),
         ],
         SPL_ASSOCIATED_TOKEN_ACCOUNT_PROGRAM_ID
-    )[0];
+    ))[0];
 }
 ```