create text_classification/README.en.md

[dantougit]

English version of README fix https://github.com/PaddlePaddle/models/issues/717

[skylarch]

根据最新的格式要求，请将英文README文档的名称改为README.md。

[CLAassistant]

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:x: 郝卓琳
:x: dantougit

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