Document supported targets and host runtime behavior

[lukewilliamboswell]

Summary

• document the five supported OS/architecture targets and current Windows limitation
• explain HTTP/TLS, TCP timeout and buffering, and SQLite connection lifecycle behavior
• link generated module docs to the runtime notes and correct stale or misspelled documentation

Testing

• ./scripts/test.py
• roc docs --output=/tmp/basic-cli-448-docs.DnBh56 platform/main.roc

Closes #448