add doc

Author: ttop32

README.md

@@ -7,7 +7,7 @@ Mouseover Translate Any Language At Once - Chrome Extension
 
 Download from [chrome web store](https://chromewebstore.google.com/detail/hmigninkgibhdckiaphhmbgcghochdjc), [Edge Extension store](https://microsoftedge.microsoft.com/addons/detail/mouse-tooltip-translator/nnodgmifnfgkolmakhcfkkbbjjcobhbl) and [Firefox Addons](https://addons.mozilla.org/en-US/firefox/addon/mouse-tooltip-translator-pdf/)
 
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 [<img alt="chrome web store" height="54px" src="doc/google.png" />](https://chrome.google.com/webstore/detail/mouse-tooltip-translator/hmigninkgibhdckiaphhmbgcghochdjc)
 [<img alt="microsoft store" height="54px" src="doc/microsoft.png" />](https://microsoftedge.microsoft.com/addons/detail/mouse-tooltip-translator/nnodgmifnfgkolmakhcfkkbbjjcobhbl)
 [<img alt="microsoft store" height="54px" src="doc/firefox_addons.png" />](https://addons.mozilla.org/en-US/firefox/addon/mouse-tooltip-translator-pdf/)