move mainnet note to top of build instructions

docs/installing.md

@@ -1,7 +1,3 @@
-# Build and run Haveno
-
-These are the steps needed to build and run Haveno. You can test it locally or on our test network using the official Haveno repository.
-
 > [!note]
 > Trying to use Haveno on mainnet?
 > 
@@ -9,6 +5,10 @@ These are the steps needed to build and run Haveno. You can test it locally or o
 > 
 > Find a third party network and use their installer or build their repository. Alternatively [create your own mainnet network](create-mainnet.md).
 
+# Build and run Haveno
+
+These are the steps needed to build and run Haveno. You can test it locally or on our test network using the official Haveno repository.
+
 ## Install dependencies
 
 On Ubuntu: `sudo apt install make wget git`