Clarify how to deal with negative profit

[szaganek]

Update https://docs.apify.com/platform/actors/publishing/monetize

• Add more thorough explanations to Actor events, memory limits, respecting user spending limits
• Add some kind of troubleshooting section that explains possible reasons for negative profit and how to deal with it
• Split the topic into more manageable chunks

[szaganek]

Related tasks:

• https://github.com/apify/apify-core/issues/28349