Update maximum support Node version advice
Update maximum support Node version advice

Testing and running fine on 6.6.
benjeffreys/hmcts-idam-proto,gavinwye/govuk_prototype_kit,paulpod/invgov,gavinwye/govuk_prototype_kit,tsmorgan/marx,karlparton/my-govuk,DilwoarH/GDS-Prototype-DM-SavedSearch,gup-dwp/pip-prototype-v2,dwpdigitaltech/ejs-prototype,benjeffreys/hmcts-idam-proto,davedark/proto-timeline,dwpdigitaltech/hrt-prototype,alphagov/govuk_prototype_kit,nhsbsa/ppc-prototype,BucksCountyCouncil/verify-local-patterns,nhsbsa/ppc-prototype,Demwunz/esif-prototype,samwake/hoddat-cofc-caseworking,abbott567/govuk_prototype_kit,Demwunz/esif-prototype,abbott567/govuk_prototype_kit,samwake/hoddat-cofc-caseworking,karlparton/my-govuk,davedark/proto-timeline,hannalaakso/accessible-timeout-warning,kenmaddison-scc/verify-local-patterns,abbott567/govuk_prototype_kit,companieshouse/ch-accounts-prototype,danblundell/verify-local-patterns,dwpdigitaltech/hrt-prototype,chrishanes/pvb_prisoner_proto,DilwoarH/GDS-Prototype-DM-SavedSearch,arminio/govuk_prototype_kit,BucksCountyCouncil/verify-local-patterns,DilwoarH/GDS-Prototype-DM-SavedSearch,Demwunz/esif-prototype,joelanman/govuk_prototype_kit,joelanman/govuk_prototype_kit,dwpdigitaltech/ejs-prototype,gup-dwp/pip-prototype-v2,chrishanes/pvb_prisoner_proto,companieshouse/ch-accounts-prototype,dwpdigitaltech/hrt-prototype,tsmorgan/marx,danblundell/verify-local-patterns,arminio/govuk_prototype_kit,hannalaakso/accessible-timeout-warning,karlparton/my-govuk,kenmaddison-scc/verify-local-patterns,tsmorgan/marx,benjeffreys/hmcts-idam-proto,BucksCountyCouncil/verify-local-patterns,alphagov/govuk_prototype_kit,chrishanes/pvb_prisoner_proto,paulpod/invgov,joelanman/govuk_prototype_kit,danblundell/verify-local-patterns,arminio/govuk_prototype_kit,hannalaakso/accessible-timeout-warning,alphagov/govuk_prototype_kit,gup-dwp/pip-prototype-v2,davedark/proto-timeline,dwpdigitaltech/ejs-prototype,kenmaddison-scc/verify-local-patterns,samwake/hoddat-cofc-caseworking,nhsbsa/ppc-prototype,paulpod/invgov