Feat/server route

[Antoine0703]

Description

For rust server :

• API Routes : GET /articles/count
• API Routes : POST /auth/register
• API Routes : POST /auth/login
• API Routes : GET /users/:id/keywords
• API Routes : POST /users/:id/keywords
• Add routes documentation in "root.md"
• Added the ability to add keywords for use in filters later on.

For scrapper :

• Code cleaning
• Added documentation