Allow EiE team to customise navigation items

[GeorgieBurr]

It’s inevitable that the wording, order, and content of the nav items will need changing over time.

It’d be good if we could make it so that the EiE team can customise these links, without needing to change the source code.

[emilydrk]

Estimate: larger than 5-7 days. Needs to be scoped and admin capability created if requested.

[chrismytton]

I accidentally commented on the wrong issue. Have moved to #174 (comment).

[crowbot]

Some afterthoughts - if we use the SYE repo to store the 'true source' plus overrides in a verification-pages compatible CSV file, interested Wikimedians in Nigeria could use it to populate Wikidata with memberships via the verification-pages (we'll have set up the data model for Nigeria as part of Concorde). So EiE don't need to become expert in Wikidata, but other people who are can see their changes to current politicians, and choose to update Wikidata as a result.