Updated secondary slot algo doc (#6297)

* Updated secondary slot algo doc

ref: https://substrate.stackexchange.com/questions/11943/why-was-babe-secondary-slot-assignment-not-implemented-in-a-round-robin-style/

* Update docs/learn/learn-consensus.md

* minor edits

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Co-authored-by: Radha <86818441+DrW3RK@users.noreply.github.com>

docs/learn/learn-consensus.md

@@ -83,10 +83,10 @@ build in some capacity until finalization kicks in and amputates a fork. See
 ### No Validators in Slot
 
 When no validators have rolled low enough in the randomness lottery to qualify for block production,
-a slot can remain seemingly blockless. We avoid this by running a secondary, round-robin style
-validator selection algorithm in the background. The validators selected to produce blocks through
-this algorithm always produce blocks. Still, these _secondary_ blocks are ignored if the same slot
-also produces a primary block from a [VRF-selected](./learn-cryptography.md#randomness) validator.
+a slot can remain seemingly blockless. Polkadot protocol runs a [secondary validator selection algorithm](https://spec.polkadot.network/sect-block-production#defn-babe-secondary-slots) in the 
+background. The validators selected through this predictable algorithm always produce 
+blocks. These _secondary_ blocks are ignored if the same slot
+has a primary block produced from a [VRF-selected](./learn-cryptography.md#randomness) validator.
 Thus, a slot can have either a _primary_ or a _secondary_ block, and no slots are ever skipped.
 
 For more details on BABE, please see the