PDA mint authority examples

tokens/pda-mint-authority/README.md

@@ -1,27 +1,5 @@
-# NFT Minter
+# PDA Mint Authority
 
-Minting NFTs is exactly the same as [minting any SPL Token on Solana](../spl-token-minter/), except for immediately after the actual minting has occurred.   
+This example is exactly the same as the `NFT Minter` example, but it changes the `mint authority` account from the payer (System Account) to a PDA.   
    
-What does this mean? Well, when you mint SPL Tokens, you can attach a fixed supply, but in most cases you can continue to mint new tokens at will - increasing the supply of that token.   
-   
-With an NFT, you're supposed to only have **one**.   
-   
-So, how do we ensure only one single token can be minted for any NFT?
-
----
-
-We have to disable minting by changing the Mint Authority on the Mint.   
-   
-> The Mint Authority is the account that is permitted to mint new tokens into supply.
-   
-If we remove this authority - effectively setting it to `null` - we can disable minting of new tokens for this Mint.   
-   
-> By design, **this is irreversible**.   
-   
----
-
-Although we can set this authority to `null` manually, we can also make use of Metaplex again, this time to mark our NFT as Limited Edition.   
-   
-When we use an Edition - such as a Master Edition - for our NFT, we get some extra metadata associated with our NFT and we also get our Mint Authority deactivated by delegating this authority to the Master Edition account.   
-   
-This will effectively disable future minting, but make sure you understand the ramifications of having the Master Edition account be the Mint Authority - rather than setting it permanently to `null`.
+💡Notice the use of `invoke_signed` for CPIs.