Update MILLISECS_PER_BLOCK comments (#7483)

* add doc comment to node template MILLISECS_PER_BLOCK

* add broken link comment

* update Babe block time link

Co-authored-by: André Silva <123550+andresilva@users.noreply.github.com>

Co-authored-by: André Silva <123550+andresilva@users.noreply.github.com>

substrate/bin/node-template/runtime/src/lib.rs

@@ -102,6 +102,12 @@ pub const VERSION: RuntimeVersion = RuntimeVersion {
 	transaction_version: 1,
 };
 
+/// This determines the average expected block time that we are targetting.
+/// Blocks will be produced at a minimum duration defined by `SLOT_DURATION`.
+/// `SLOT_DURATION` is picked up by `pallet_timestamp` which is in turn picked
+/// up by `pallet_aura` to implement `fn slot_duration()`.
+///
+/// Change this to adjust the block time.
 pub const MILLISECS_PER_BLOCK: u64 = 6000;
 
 pub const SLOT_DURATION: u64 = MILLISECS_PER_BLOCK;

substrate/bin/node/runtime/src/constants.rs

@@ -50,7 +50,7 @@ pub mod time {
 	/// always be assigned, in which case `MILLISECS_PER_BLOCK` and
 	/// `SLOT_DURATION` should have the same value.
 	///
-	/// <https://research.web3.foundation/en/latest/polkadot/BABE/Babe/#6-practical-results>
+	/// <https://research.web3.foundation/en/latest/polkadot/block-production/Babe.html#-6.-practical-results>
 	pub const MILLISECS_PER_BLOCK: Moment = 3000;
 	pub const SECS_PER_BLOCK: Moment = MILLISECS_PER_BLOCK / 1000;