[FunC] Pending issues in Cookbook

[jeshecdom]

The following three algorithms are unclear on how to edit them or fix the explanation. More information is needed:

• How to update the smart contract logic (no idea what to do with the TypeScript snippets... how they are used?)
• Modulo operations (completely confusing, no idea what the algorithm is talking about AT ALL)
• Generate an external address (puzzled by this one... what is the purpose of an external address and why do they need to be generated?)

Missing links (search the page for the text):

• Random number generation section
• Sending messages page (Referring to old page https://docs.ton.org/v3/documentation/smart-contracts/message-management/sending-messages)