Lang???.gf: exclude Documentation from present mode

The Documentation module is excluded from present mode in abstract/Lang.gf,
so it needs to be excluded in the corresponding concrete syntaxes too
to avoid problems.

src/spanish/LangSpa.gf

@@ -3,7 +3,7 @@
 concrete LangSpa of Lang = 
   GrammarSpa,
   LexiconSpa
-  ,DocumentationSpa
+  ,DocumentationSpa --# notpresent
   ,ConstructionSpa
   ** {