cleaned up API comments for document

lib/resource-1.0/abstract/Sentence.gf

@@ -6,7 +6,8 @@ abstract Sentence = Cat ** {
 
 -- The $NP VP$ predication rule form a clause whose linearization
 -- gives a table of all tense variants, positive and negative.
--- Clauses are converted to $S$ (with fixed tense) in [Tensed Tensed.html].
+-- Clauses are converted to $S$ (with fixed tense) with the
+-- $UseCl$ function below.
 
   fun
     PredVP    : NP -> VP -> Cl ;         -- John walks
@@ -53,7 +54,7 @@ abstract Sentence = Cat ** {
 
 -- These are the 2 x 4 x 4 = 16 forms generated by different
 -- combinations of tense, polarity, and
--- anteriority, which are defined in [Tense Tense.html].
+-- anteriority, which are defined in [``Common`` Common.html].
 
   fun
     UseCl  : Tense -> Ant -> Pol -> Cl  -> S ;