spec(consensus/pbts): update description for introduced parameters.

spec/abci/abci++_app_requirements.md

@@ -581,9 +581,10 @@ These are the current consensus parameters (as of v0.37.x):
 5. [EvidenceParams.MaxBytes](#evidenceparamsmaxbytes)
 6. [ValidatorParams.PubKeyTypes](#validatorparamspubkeytypes)
 7. [VersionParams.App](#versionparamsapp)
+8. [SynchronyParams.Precision](#synchronyparamsprecision)
+9. [SynchronyParams.MessageDelay](#synchronyparamsmessagedelay)
+
 <!--
- 6. [SynchronyParams.MessageDelay](#synchronyparamsmessagedelay)
-7. [SynchronyParams.Precision](#synchronyparamsprecision)
 8. [TimeoutParams.Propose](#timeoutparamspropose)
 9. [TimeoutParams.ProposeDelta](#timeoutparamsproposedelta)
 10. [TimeoutParams.Vote](#timeoutparamsvote)
@@ -678,26 +679,26 @@ The parameter restricts the type of keys validators can use. The parameter uses
 ##### VersionParams.App
 
 This is the version of the ABCI application.
-<!--
-##### SynchronyParams.MessageDelay
-
-This sets a bound on how long a proposal message may take to reach all
-validators on a network and still be considered valid.
-
-This parameter is part of the
-[proposer-based timestamps](../consensus/proposer-based-timestamp)
-(PBTS) algorithm.
-
 
 ##### SynchronyParams.Precision
 
 This sets a bound on how skewed a proposer's clock may be from any validator
 on the network while still producing valid proposals.
 
-This parameter is part of the
-[proposer-based timestamps](../consensus/proposer-based-timestamp)
-(PBTS) algorithm.
+This parameter is used by the
+[Proposer-Based Timestamps (PBTS)](../consensus/proposer-based-timestamp/README.md)
+algorithm.
 
+##### SynchronyParams.MessageDelay
+
+This sets a bound on how long a proposal message may take to reach all
+validators on a network and still be considered valid.
+
+This parameter is used by the
+[Proposer-Based Timestamps (PBTS)](../consensus/proposer-based-timestamp/README.md)
+algorithm.
+
+<!--
 
 ##### TimeoutParams.Propose