Fix "make dist" target, now that some of the documentation files are gone.
Fix "make dist" target, now that some of the documentation files are gone.

hlinnaka/psqlodbc,Distrotech/psqlodbc,treasure-data/prestogres-odbc,gavioto/psqlodbc,treasure-data/prestogres-odbc,hlinnaka/psqlodbc,Distrotech/psqlodbc,gavioto/psqlodbc,Distrotech/psqlodbc,gavioto/psqlodbc,hlinnaka/psqlodbc,treasure-data/prestogres-odbc