UPDATE README

We believe that the loss of the "What is NPOI" section is not a work error. Due to the authorization of the upstream project author, removing this information does not violate the agreement or license. Because the upstream project has fully explained the relationship between NPOI and Apache POI. Here we will add it back.

README.md

@@ -48,6 +48,16 @@ We don't intend to spend more time entangled with tony qu. After discussing with
 
 ---
 
+## What is NPOI ?
+
+NPOI is the .NET version of POI Java project at http://poi.apache.org/. POI is an open source project which can help you read/write xls, doc, ppt files. It has a wide application.
+
+For example, you can use it to
+* generate a Excel report without Microsoft Office suite installed on your server and more efficient than call Microsoft Excel ActiveX at background;
+* extract text from Office documents to help you implement full-text indexing feature (most of time this feature is used to create search engines). 
+* extract images from Office documents
+* generate Excel sheets that contains formulas
+
 ## Install NuGet Package
 
 ```powershell

README.zh-CN.md

@@ -30,6 +30,15 @@ This project is for NPOI Core. NPOI is still under at [https://github.com/tonyqu
 
 ---
 
+## 什么是 NPOI？
+
+NPOI 是 [Apache POI](https://github.com/poi) 项目的 .NET 版本。POI 是一个开源项目，能帮助你读/写 xls、doc、ppt 等文件。它具有广泛用途，如：
+
+* 在服务器未安装 Microsoft Office 套件的情况下生成 Excel 报告，并且比在后台调用 Microsoft Excel ActiveX 效率更高；
+* 从 Office 文档中提取文本，以帮助你实现全文索引功能（大多数情况下，此功能用于创建搜索引擎）；
+* 从 Office 文档中提取图像；
+* 生成包含公式的 Excel 工作表。
+
 ## 安装 NuGet 包
 
 ```powershell