docs: add 20 language links of README

[shps951023]

Dear team, PR adds 20 languages link to the README and user can easily to access translated READEME. it supports google/bing multiple languages SEO search.

You can check page demo https://openaitx.github.io/view.html?user=Portkey-AI&project=gateway&lang=ja

OpenAiTx is free and open-source : https://github.com/OpenAiTx/OpenAiTx

e.g. My project MiniExcel