[ci skip] packaging: small fix in packaging instruction

Author: kulaginm

Diff for: packaging/Readme.md

@@ -9,7 +9,7 @@ make pkg
 
 To build binaries for PostgresPro Standart or Enterprise, a pgpro.tar.bz2 with latest git tree must be preset in `packaging/tarballs` directory:
 ```
-cd packaging/tarballs
+cd packaging/pkg/tarballs
 git clone pgpro_repo pgpro
 tar -cjSf pgpro.tar.bz2 pgpro
 ```