Updating Bridge documentation

[loonggamma]

TO MERGE after Bridge V2 deployment

• added BSC info to the Home and Instructions pages.

To do:

• [x] when deployed add SC and Token information for BSC
• [x] update Instructions for service fee when implemented (confirmation step)
• [x] Update Architecture and Security for k of n update

[loonggamma]

@leoloco can you review my changes and add the needed info for the Architecture and Security update for k of n?