Update the content of training best practice for single node (#1845) (#1847)

* Update link in training_best_practice.
test=develop

* Update the documentation.
test=develop

* Refine the format.
test=develop

* Change the format of title.
test=develop

doc/fluid/advanced_guide/performance_improving/analysis_tools/index_cn.rst

+.. _api_guide_analysis_tools:
+
 ###############
 性能优化分析及工具
 ###############