add agent module blurb

Author: eeelllccc

doc/markov/index.mld

@@ -58,4 +58,8 @@ kicks off an infinite loop modelling an Markov Decision Process (MDP). Each iter
 + infering a method to next measure the state of the MDP (in other words producing an {e observer})
 + executing the action
 
-{b The implementation of this loop is included in the [markov] library.} It is found in {{!/markov/src/agent.ml.html#module-Make}the implementation} of the [Agent.Make] functor.
+{b The implementation of this loop is included in the [markov] library.} It is found in the implementation of the [Agent.Make] functor.
+
+{1 Reference Implementation}
+The {{!/blue/page-index}blue} library implements the [Markov] interfaces (albeit with a simple implementation).
+

markov/agent.mli

@@ -1,4 +1,6 @@
-(** Exposes the functor [Agent.Make] **)
+(** Exposes the functor [Agent.Make] which returns an [Agent.S] module that is parameterised by the provided implementations of [Agent.MarkovCompressorType], [Agent.RewardType] and [Agent.RLPolicyType].
+
+[Agent.S.act initial_policy] commences an infinite loop using the policy to take actions and produce {e observers} (functions returning a {e state}). When the observer resolves to a state, the loop repeats. *)
 
 (** Handle the continuous-time stream of information from a system and compress the information into a Markovian state representation such that the sequence of states returned by sequential calls to [observe] have the Markov property. *)
 module type MarkovCompressorType = sig