[FEATURE]: update main FEGA text

### Feature type(s)

Content modification

### Location

https://ega-archive.github.io/FEGA-onboarding/#what-is-federated-ega-fega

### Description of the change

match text here: https://ega-archive.org/about/projects-and-funders/federated-ega/

### Reason for the change

text is out of date