H1 Tag Changes to the Homepage

[Govej]

Looking to make SEO changes to the SDG data site, first obvious point are the H1 tags on the site, I'll create a list for further changes to Goal pages but for now the homepage change should be fine to make.

Instead of "17 goals to transform our world" which has very low search volume, I suggest changing it to "UK Data for the Sustainable Development Goals" or some variation to include high search volume keywords. This may require further changes to the rest of the text shown to avoid keyword stuffing.