Update tap.rst

[richardgmcmahon]

small change to docs in 3. Using TAP+ to connect other TAP services

unsupported
print(table.get_name())

corrected to:

print(table.get_qualified_name())

[bsipocz]

Thanks @richardgmcmahon!

[bsipocz]

Small comment: while we don't make TapPlus a private functionality its purpose is to serve the ESA modules in astroquery only and we recommend using the TAP functionalities from the pyvo package instead. Long term we plan to consolidate the two implementations into one and deprecate and remove astroquery.utils.tap.