add Features on index

Can we load feature text from .md or .yml ?

• add Froggit Features section on index
• add Features link on header

Features list are here : https://lydra.systeme.io/froggit-beta-inscription

Inspiration:

• https://github.com/kamilkisiela/graphql-inspector
• https://graphql-inspector.com/
• https://the-guild.dev/services