replace MG solver by SAAMG

fieldsolvers.asciidoc

@@ -442,7 +442,7 @@ Default value is 100.
 === Define Preconditioner Behavior
 
 The behavior of the preconditioner can be: `STD`, `HIERARCHY` or
-`REUSE`. This argument is only relevant when using the `MG` solver and
+`REUSE`. This argument is only relevant when using the `SAAMG` solver and
 should *only be set if the consequences to simulation and solver are
 evident*. A short description is given in the
 Table below.

geometry.asciidoc

@@ -14,7 +14,7 @@ endif::[]
 
 At present the `GEOMETRY` command is still an *experimental feature*
 which is not to be used by the general user. It can only be used to
-specify boundaries for the MG Solver. The command can be used in two
+specify boundaries for the `SAAMG` Solver. The command can be used in two
 modes:
 
 1.  specify a H5hut file holding the surface mesh of a complicated