Reword where to get peers from in understanding-config-files.md

Fixes input-output-hk/ouroboros-network#3691

doc/getting-started/understanding-config-files.md

@@ -19,7 +19,8 @@ Tells your node to which nodes in the network it should talk to. A minimal versi
 
 * `valency` determines how many active (hot) outgoing connections to different resolved IP addresses your node should maintain when a DNS address is specified. The valency setting has no effect when setting an IP address, except when using `0` to disable the connection.
 
-Your __block-producing__ node must __ONLY__ talk to your __relay nodes__, and the relay node should talk to other relay nodes in the network. Go to our telegram channel to find out IP addresses and ports of peers.
+Your __block-producing__ node must __ONLY__ talk to your __relay nodes__, and
+the relay node should talk to other relay nodes in the network.
 
 #### The P2P topology.json file
 
@@ -97,6 +98,17 @@ signal, `cardano-node` will re-read the file and restart all DNS resolution. Ple
 One can disable ledger peers by setting the `useLedgerAfterSlot` to a negative
 value.
 
+If you are synchronizing the network for the first time, please connect to IOG
+relays `relays-new.cardano-mainnet.iohkdev.io` by adding it to your local root
+peers and set `useLedgerAfterSlot` to `0` (to disable ledger peers).  You can
+use different relays as long as you trust them to provide you the honest chain.
+When the node is synced, you can remove it from the local root peers, you
+should also manually check if other stake pool relays are on the same chain as
+you are.  Once you enabled ledger peers by setting `useLedgerAfterSlot` the
+node will connect to relays registered on the chain, and churn through them by
+randomly picking new peers (weighted by stake distribution) and forgetting 20%
+least performing ones.
+
 #### The genesis.json file
 
 The genesis file is generated with the `cardano-cli` by reading a `genesis.spec.json` file, which is out of scope for this document.