Reduce needlessly massive images

[lukaw3d]

List of files >1MB:

• 1.23 MB https://github.com/oasisprotocol/docs/blob/main/docs/oasis-network-primer/images/Uni_Map_updated.png
• 1.47 MB https://github.com/oasisprotocol/docs/blob/main/docs/general/images/manage-tokens/wormhole/switch_to_emerald.png
• 1.54 MB https://github.com/oasisprotocol/docs/blob/main/docs/general/images/manage-tokens/wormhole/send_tokens_to_wormhole.png
• 1.58 MB https://github.com/oasisprotocol/docs/blob/main/docs/oasis-network-primer/images/Group_8.png
• 1.63 MB https://github.com/oasisprotocol/docs/blob/main/docs/general/images/manage-tokens/wormhole/redeem_tokens.png
• 1.64 MB https://github.com/oasisprotocol/docs/blob/main/docs/general/images/manage-tokens/wormhole/send_tokens.png
• 2.11 MB https://github.com/oasisprotocol/docs/blob/main/docs/general/images/manage-tokens/wormhole/select_source_dest_amount.png
• 2.25 MB https://github.com/oasisprotocol/docs/blob/main/docs/general/images/manage-tokens/wormhole/index.png
• 2.26 MB https://github.com/oasisprotocol/docs/blob/main/docs/general/images/wallet/ledger/6b_ledger_oasis_ready.png
• 2.82 MB https://github.com/oasisprotocol/docs/blob/main/docs/general/images/manage-tokens/wormhole/connect_wallet.png
• 2.89 MB https://github.com/oasisprotocol/docs/blob/main/docs/general/images/manage-tokens/wormhole/redeem_tokens2.png
• 3.63 MB https://github.com/oasisprotocol/docs/blob/main/docs/oasis-network-primer/images/ecosystem-network-01.jpeg

[tjanez]

After #146 , 1 more image larger than 1 MB remains:

• 1.8 MB https://github.com/oasisprotocol/docs/blob/main/docs/oasis-network-primer/images/ecosystem-network-01.jpg