Fix inconsistency in intro-to-custom-onchain-programs.md (#544)

* Fix inconsistency in intro-to-custom-onchain-programs.md

* Update intro-to-custom-onchain-programs.md

* Update content/courses/intro-to-solana/intro-to-custom-onchain-programs.md

---------

Co-authored-by: Mike MacCana <mike.maccana@gmail.com>

content/courses/intro-to-solana/intro-to-custom-onchain-programs.md

@@ -17,15 +17,9 @@ invoked in the onchain program.
 
 ### Instructions
 
-In previous chapters, we used:
-
-- The `SystemProgram.transfer()` function from `@solana/web3.js` to make an
-  instruction for the System program to transfer SOL.
-- The `mintTo()` and `transfer()` functions from `@solana/spl-token`, to make
-  instructions to the Token program to mint and transfer tokens
-- The `createCreateMetadataAccountV3Instruction()` function from
-  `@metaplex-foundation/mpl-token-metadata@2` to make instructions to Metaplex
-  to create token Metadata.
+In previous lessons, we used the `SystemProgram.transfer()` function from 
+`@solana/web3.js`, which creates an instruction for the System program to 
+transfer SOL.
 
 When working with other programs, however, you'll need to create instructions
 manually. With `@solana/web3.js`, you can create instructions with the