[ENH] generate separate page for each BEP

[Remi-Gau]

• closes BEP table too wide: becomes unreadable #567 : more narrow BEP table
• relates to list somewhere that each BEP has their own, dedicated BIDS maintainer as a point of contact #466 : add a maintainer for each BEP
• relates to For each active BEP add the "chat" channel were conversation may be happening. #380 : start listing communication channel for each BEP