update solenv READNE

- gbuild is not "shiny new" anymore -- its the default
- hint at solenv/doc/gbuild

Change-Id: I20be4f10c68a935bd4ec99c4a95714ab08f80ca0

solenv/README

@@ -16,8 +16,7 @@ bin/
         do a local install for the smoketest.
 
 gbuild/
-	the (shiny new) gnumake build makefile fragments we are
-	migrating the codebase to use.
+    implementation of the LibreOffice build system
     See gbuild/README for more info.
 
 gdb/

solenv/gbuild/README

@@ -9,4 +9,9 @@ See
 	https://web.archive.org/web/20130911015536/http://wiki.openoffice.org/wiki/Build_Environment_Effort/Module_Migration
 for an archived overview of the new build system.
 
-
+See
+   ./solenv/doc/gbuild
+for a commented class/API heirachy of gbuild written in C++ syntax. It was not
+intended for any use beyond to generate nicelooking docs with the doxygen
+doxygen documentation generator from it. It likely is quite outdated these
+days.