docs: record smoke-test failure modes (cookbook git, 429, eval tokens)

[sfc-gh-kganesan]

Summary

From a QA6 walk of every catalog recipe:

• Cookbook install via git+https fails when git rewrites GitHub to SSH. Document the HTTPS clone workaround.
• After cancel, capacity can still show a full in_use_gpus while list --status running is empty; create then 429s. Document wait/retry.
• MATH eval with a tiny max_tokens is a false failure. Call out the 4096 default.
• Inference README job-config schematic is not valid JSON (// comments).

Related copy is on #8 (SFT 2-step success criteria, GRPO remove_constant_reward_groups) and #9 (recipe install fallback).

Test plan

• Troubleshooting page matches what capacity / list show after cancel
• Eval docs no longer imply max_tokens=64 is a valid MATH smoke