Document TrivialGModule

It has been around forever but was undocumented.

doc/ref/meataxe.xml

@@ -100,6 +100,15 @@ moved point (see&nbsp;<Ref Attr="LargestMovedPoint" Label="for a list or collect
 </Description>
 </ManSection>
 
+<ManSection>
+<Func Name="TrivialGModule" Arg='G, F'/>
+
+<Description>
+Called with a group <A>G</A> and a field <A>F</A> (<A>F</A> may be infinite),
+<Ref Func="TrivialGModule"/> returns the trivial module over <A>F</A>.
+</Description>
+</ManSection>
+
 <ManSection>
 <Func Name="TensorProductGModule" Arg='m1, m2'/>
 

tst/testinstall/meataxe.tst

@@ -40,6 +40,15 @@ gap> Display(MTX.IsomorphismModules(M,M));
  . 1 .
  . . 1
 
+#
+# Trivial module
+#
+gap> G:=SL(3,3);;
+gap> TrivialGModule(G, GF(2));
+rec( IsOverFiniteField := true, dimension := 1, field := GF(2), 
+  generators := [ <an immutable 1x1 matrix over GF2>, 
+      <an immutable 1x1 matrix over GF2> ], isMTXModule := true )
+
 #
 #
 #