Updated "Downloads" section of documentation.
Updated "Downloads" section of documentation.

Added a note that the full source tarball contains a copy of the documentation, and noted that the documentation could be downloaded separately from Sourceforge.

mohamed-ali/PyTables,mohamed-ali/PyTables,FrancescAlted/PyTables,cpcloud/PyTables,andreabedini/PyTables,joonro/PyTables,andreabedini/PyTables,tp199911/PyTables,rdhyee/PyTables,tp199911/PyTables,jack-pappas/PyTables,FrancescAlted/PyTables,jennolsen84/PyTables,joonro/PyTables,avalentino/PyTables,jack-pappas/PyTables,rdhyee/PyTables,PyTables/PyTables,rabernat/PyTables,jennolsen84/PyTables,cpcloud/PyTables,jack-pappas/PyTables,jack-pappas/PyTables,jack-pappas/PyTables,gdementen/PyTables,joonro/PyTables,gdementen/PyTables,rdhyee/PyTables,avalentino/PyTables,dotsdl/PyTables,gdementen/PyTables,mohamed-ali/PyTables,andreabedini/PyTables,rabernat/PyTables,cpcloud/PyTables,cpcloud/PyTables,joonro/PyTables,jennolsen84/PyTables,PyTables/PyTables,tp199911/PyTables,dotsdl/PyTables,gdementen/PyTables,rdhyee/PyTables,PyTables/PyTables,rabernat/PyTables,avalentino/PyTables,dotsdl/PyTables,andreabedini/PyTables,tp199911/PyTables,FrancescAlted/PyTables,dotsdl/PyTables,mohamed-ali/PyTables,jennolsen84/PyTables,rabernat/PyTables