[trac764] minor doxygen fixes: add log/compiler to INPUT; make sure

the overview will be the documentation for the file (not for a specific
function)

doc/Doxyfile

@@ -570,8 +570,8 @@ WARN_LOGFILE           =
 
 INPUT                  = ../src/lib/cc ../src/lib/config \
     ../src/lib/cryptolink ../src/lib/dns ../src/lib/datasrc \
-    ../src/bin/auth ../src/bin/resolver ../src/lib/bench \
-    ../src/lib/log ../src/lib/asiolink/ ../src/lib/nsas \
+    ../src/bin/auth ../src/bin/resolver ../src/lib/bench ../src/lib/log \
+    ../src/lib/log/compiler ../src/lib/asiolink/ ../src/lib/nsas \
     ../src/lib/testutils ../src/lib/cache ../src/lib/server_common/ \
     ../src/bin/sockcreator/ ../src/lib/util/ \
     ../src/lib/resolve ../src/lib/acl

src/lib/log/compiler/message.cc

@@ -43,6 +43,7 @@ using namespace isc::util;
 
 static const char* VERSION = "1.0-0";
 
+/// \file log/compiler/message.cc
 /// \brief Message Compiler
 ///
 /// \b Overview<BR>