Add introduction.rst of best_practices
fix typo
Merge pull request #320 from brtriver/add-best-practices-introduction

Add introduction.rst of best_practices
Fix 推敲

* typo
* recommendation を 助言 から 推奨案 に
* 言い回しがおかしな表現を自然な日本語に
Merge pull request #321 from brtriver/fix-best-practices-introduction

Fix introduction の 推敲
[best practice] add index.rst
[best practice] add forms.rst
[best practice] add templates.rst
[best practice] add configuration.rst
[best practice] add business-logic.rst
[best practice] "traditionaly" の訳語をweb-assetsと統一