Add third-party OC4IDS tools to documentation

[pindec]

Nuevo Leon's Infraestructura Abierta is an open-source OC4IDS visualisation tool and a good example of displaying infrastructure projects (from OC4IDS data), related contracting processes (from OCDS records data) and aggregated OC4IDS indicators (from OC4IDS data).

We should add it (and any other examples that emerge) to the documentation.

@jpmckinney suggested a new page under the guidance section if there is no obvious location. I think a new page is the best option here, since the tool may be applicable to both Publishing data from an infrastructure transparency portal and Using data from procurement systems for infrastructure monitoring. There is an existing tools section in the latter (listing OCDS tools), which should also point to the new page.

[duncandewhurst]

Sounds good! We can also link to the forthcoming technical case study on Nuevo Leon's implementation.

[pindec]

We also had a request from a potential government implementer for examples of OC4IDS publishers who've shown the benefits of using it.

We can link to CoST Ukraine's analytics portal (English version), which provides users with an interactive system to explore and compare multiple indicators (including comparisons of cost of road per kilometre for type of road works, procurement analytics, market and supplier data), and the ability to explore project details.

In addition to Nuevo Leon's source code and the technical case study, we could link to the front-end Infraestructura Abierta / Open Infrastructure portal and the OC4IDS aggregated indicators page.

We should also link to resources like OC4IDS data use/indicators document and spreadsheet