Correct AMIP data regrid service info

The page https://pcmdi.llnl.gov/mips/amip/details/#Appendix_2 erroneously notes that a regrid service is available. This has not been available for a number of years, rather we provide 1x1 standard gridded data for use (see https://esgf-node.llnl.gov/search/input4mips/?institution_id=PCMDI&target_mip_list=CMIP&query=version:20190124).

This information will need to be corrected