fix accessibility issues and typos in the section titles
fix accessibility issues and typos in the section titles

alphagov/trade-tariff-backend,bitzesty/trade-tariff-backend,alphagov/trade-tariff-backend,bitzesty/trade-tariff-backend,leftees/trade-tariff-backend,leftees/trade-tariff-backend,leftees/trade-tariff-backend,bitzesty/trade-tariff-backend,alphagov/trade-tariff-backend