Add documentation for creating a release
Add documentation for creating a release

Add steps for creating a release to CONTRIBUTING.md.

hannalaakso/accessible-timeout-warning,hannalaakso/accessible-timeout-warning,benjeffreys/hmcts-idam-proto,alphagov/govuk_prototype_kit,dwpdigitaltech/hrt-prototype,alphagov/govuk_prototype_kit,joelanman/govuk_prototype_kit,DilwoarH/GDS-Prototype-DM-SavedSearch,joelanman/govuk_prototype_kit,benjeffreys/hmcts-idam-proto,joelanman/govuk_prototype_kit,hannalaakso/accessible-timeout-warning,dwpdigitaltech/hrt-prototype,alphagov/govuk_prototype_kit,DilwoarH/GDS-Prototype-DM-SavedSearch,dwpdigitaltech/hrt-prototype,gavinwye/govuk_prototype_kit,gavinwye/govuk_prototype_kit,benjeffreys/hmcts-idam-proto,DilwoarH/GDS-Prototype-DM-SavedSearch