add new coin logo (#262)
add new coin logo (#262)

* remove old logo

* add new COIN logo

* remove coin logo

* add new coin logo
OpenAstronomy/openastronomy.github.io,Cadair/openastronomy.github.io,Cadair/openastronomy.github.io,dpshelio/openastronomy.github.io,dpshelio/openastronomy.github.io,OpenAstronomy/openastronomy.github.io,Cadair/openastronomy.github.io,OpenAstronomy/openastronomy.github.io,dpshelio/openastronomy.github.io