Write a guide for pulling vesting data

[PaulRBerg]

Write a mini guide that shows how to pull vesting data from Sablier contracts, what functions to focus on (e.g. streamedAmountOf, etc.)

This is relevant for our integrations with CMC, CoinGecko, etc.

CC @sablier-labs/business

[smol-ninja]

I have written a guide to pull vesting information. You can see the preview here. Please let me know what you think.