Clarify what this repository is in README and about

[bfabio]

The documentation is not really clear on what this repository contains.

The name is dati-semantic-frontend .

The about says "Frontend for the NDC semantic repository"

The introduction in the README says:

Let's color code the sections, in red 🟥 the sections NOT describing this repo, in blue the ones describing this repo 🟦

Not only the blue 🟦 parts, significant for this repo, are less then the red 🟥 parts, but they also repeat the same information in some places

Expected

IMO this repo can be simply very well described by "schema.gov.it frontend site / code" in the About section and in the README introduction.