2.7.2rc8: Bug fixes and document updates

What's Changed

• [2.7] Add comprehensive timeout documentation [skip ci] by @chesterxgchen in #4083
• [2.7] Rename recipe argument 'initial_model' to 'model' by @chesterxgchen in #4144
• [2.7] Fix arg docstring [skip ci] by @YuanTingHsieh in #4145
• [2.7] added comment in job_recipe notebook by @pcnudde in #4147
• [2.7] CIFAR-10 Experiment Tracking Instructions Corrections by @holgerroth in #4148
• [2.7] Recipe: support relative initial_ckpt and API enhancements by @chesterxgchen in #4155
• [2.7] Revert model back to initial model for Job API by @YuanTingHsieh in #4153
• [2.7] Fix fed eval example by @YuanTingHsieh in #4152
• [2.7] Rename sklearn recipe args by @YuanTingHsieh in #4154
• [2.7] Recipe API: use class_path for model dict, rename validate_ckpt by @YuanTingHsieh in #4156

Full Changelog: 2.7.2rc7...2.7.2rc8