Fix doc links

docs/modules/ROOT/pages/gsn.adoc

@@ -2,7 +2,7 @@
 
 The https://gsn.openzeppelin.com[Gas Station Network] allows you to build apps where you pay for your users transactions, so they do not need to hold Ether to pay for gas, easing their onboarding process. In this guide, we will learn how to write smart contracts that can receive transactions from the GSN, by using OpenZeppelin Contracts.
 
-If you're new to the GSN, you probably want to first take a look at the xref:learn::on-gsn.adoc[overview of the system] to get a clearer picture of how gasless transactions are achieved. Otherwise, strap in!
+If you're new to the GSN, you probably want to first take a look at the xref:learn::sending-gasless-transactions.adoc[overview of the system] to get a clearer picture of how gasless transactions are achieved. Otherwise, strap in!
 
 == Receiving a Relayed Call
 

docs/modules/ROOT/pages/index.adoc

@@ -35,7 +35,7 @@ contract MyContract is Ownable {
 }
 ----
 
-TIP: If you're new to smart contract development, head to xref:learn::writing-smart-contracts.adoc[Writing Smart Contracts] to learn about creating a new project and compiling your contracts.
+TIP: If you're new to smart contract development, head to xref:learn::developing-smart-contracts.adoc[Developing Smart Contracts] to learn about creating a new project and compiling your contracts.
 
 To keep your system secure, you should **always** use the installed code as-is, and neither copy-paste it from online sources, nor modify it yourself.