Alephium token list

Token metadata example: https://github.com/alephium/token-list/blob/master/tokens/mainnet.json#L4-L11

• All of the token logos should stay in the folder logos with the same naming as the token symbol
• The token uri in the token metadata should use the Github logo uri: https://raw.githubusercontent.com/alephium/token-list/master/logos/<symbol>.png
• The token uri will be available once your PR is merged to master branch